APH1A

UniProt ID: Q96BI3
Organism: Homo sapiens
Review Status: COMPLETE
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Gene Description

APH1A encodes gamma-secretase subunit APH-1A, a multipass membrane protein and essential non-catalytic component of the gamma-secretase intramembrane protease complex. Together with a presenilin catalytic subunit, nicastrin, and PSENEN/PEN-2, APH1A supports complex assembly, stability, and activity toward membrane substrates including APP and Notch receptors. APH1A is enriched in endoplasmic-reticulum and cis-Golgi membranes and participates in regulated intramembrane proteolysis within membrane and endomembrane compartments.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0070765 gamma-secretase complex
IBA
GO_REF:0000033 		ACCEPT
Summary: APH1A is an established non-catalytic subunit of the gamma-secretase complex with presenilin, nicastrin, and PSENEN/PEN-2.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0034205 amyloid-beta formation
IBA
GO_REF:0000033 		ACCEPT
Summary: APH1A-containing gamma-secretase participates in APP processing that generates amyloid-beta-related products.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0016485 protein processing
IBA
GO_REF:0000033 		ACCEPT
Summary: This captures the core regulated intramembrane processing activity of the APH1A-containing gamma-secretase complex.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0030674 protein-macromolecule adaptor activity
IBA
GO_REF:0000033 		ACCEPT
Summary: APH1A acts as a non-catalytic assembly/adaptor subunit that helps stabilize and organize active gamma-secretase complexes.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0007220 Notch receptor processing
IBA
GO_REF:0000033 		ACCEPT
Summary: APH1A supports gamma-secretase-dependent Notch receptor processing and release of Notch intracellular domains.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0007219 Notch signaling pathway
IBA
GO_REF:0000033 		ACCEPT
Summary: Notch signaling is a downstream pathway output of gamma-secretase-mediated Notch receptor processing.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0005789 endoplasmic reticulum membrane
IEA
GO_REF:0000044 		ACCEPT
Summary: This membrane or endomembrane location is consistent with APH1A as a multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
Reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, Golgi, endosomal, and general membrane localizations are consistent with the curated biology.
GO:0006508 proteolysis
IEA
GO_REF:0000117 		MODIFY
Summary: Generic proteolysis is too broad for APH1A; the supported process is gamma-secretase-dependent intramembrane processing of membrane substrates.
Reason: Replace the broad proteolysis term with the more specific regulated intramembrane-processing terms supported for gamma-secretase.
GO:0016020 membrane
IEA
GO_REF:0000002 		ACCEPT
Summary: This membrane or endomembrane location is consistent with APH1A as a multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
Reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, Golgi, endosomal, and general membrane localizations are consistent with the curated biology.
GO:0016485 protein processing
IEA
GO_REF:0000120 		ACCEPT
Summary: This captures the core regulated intramembrane processing activity of the APH1A-containing gamma-secretase complex.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0032580 Golgi cisterna membrane
IEA
GO_REF:0000044 		ACCEPT
Summary: This membrane or endomembrane location is consistent with APH1A as a multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
Reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, Golgi, endosomal, and general membrane localizations are consistent with the curated biology.
GO:0070765 gamma-secretase complex
IEA
GO_REF:0000117 		ACCEPT
Summary: APH1A is an established non-catalytic subunit of the gamma-secretase complex with presenilin, nicastrin, and PSENEN/PEN-2.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0005515 protein binding
IPI
PMID:12297508
Mammalian APH-1 interacts with presenilin and nicastrin and ... 		MARK AS OVER ANNOTATED
Summary: The interaction evidence is compatible with APH1A complex membership, but generic protein binding is not an informative molecular function for this gene.
Reason: Prefer complex membership and adaptor/activator terms over a broad protein-binding annotation.
GO:0005515 protein binding
IPI
PMID:18201567
Cellular localization of Nicastrin affects amyloid beta spec... 		MARK AS OVER ANNOTATED
Summary: The interaction evidence is compatible with APH1A complex membership, but generic protein binding is not an informative molecular function for this gene.
Reason: Prefer complex membership and adaptor/activator terms over a broad protein-binding annotation.
GO:0005515 protein binding
IPI
PMID:19376115
An alternative spliced mouse presenilin-2 mRNA encodes a nov... 		MARK AS OVER ANNOTATED
Summary: The interaction evidence is compatible with APH1A complex membership, but generic protein binding is not an informative molecular function for this gene.
Reason: Prefer complex membership and adaptor/activator terms over a broad protein-binding annotation.
GO:0005515 protein binding
IPI
PMID:23864651
The identification of novel proteins that interact with the ... 		MARK AS OVER ANNOTATED
Summary: The interaction evidence is compatible with APH1A complex membership, but generic protein binding is not an informative molecular function for this gene.
Reason: Prefer complex membership and adaptor/activator terms over a broad protein-binding annotation.
GO:0005515 protein binding
IPI
PMID:25394380
G206D Mutation of Presenilin-1 Reduces Pen2 Interaction, Inc... 		MARK AS OVER ANNOTATED
Summary: The interaction evidence is compatible with APH1A complex membership, but generic protein binding is not an informative molecular function for this gene.
Reason: Prefer complex membership and adaptor/activator terms over a broad protein-binding annotation.
GO:0005515 protein binding
IPI
PMID:26280335
An atomic structure of human Ξ³-secretase. 		MARK AS OVER ANNOTATED
Summary: The interaction evidence is compatible with APH1A complex membership, but generic protein binding is not an informative molecular function for this gene.
Reason: Prefer complex membership and adaptor/activator terms over a broad protein-binding annotation.
GO:0005515 protein binding
IPI
PMID:30559186
Bax inhibitor 1 is a Ξ³-secretase-independent presenilin-bind... 		MARK AS OVER ANNOTATED
Summary: The interaction evidence is compatible with APH1A complex membership, but generic protein binding is not an informative molecular function for this gene.
Reason: Prefer complex membership and adaptor/activator terms over a broad protein-binding annotation.
GO:0005515 protein binding
IPI
PMID:32296183
A reference map of the human binary protein interactome. 		MARK AS OVER ANNOTATED
Summary: The interaction evidence is compatible with APH1A complex membership, but generic protein binding is not an informative molecular function for this gene.
Reason: Prefer complex membership and adaptor/activator terms over a broad protein-binding annotation.
GO:0005515 protein binding
IPI
PMID:32814053
Interactome Mapping Provides a Network of Neurodegenerative ... 		MARK AS OVER ANNOTATED
Summary: The interaction evidence is compatible with APH1A complex membership, but generic protein binding is not an informative molecular function for this gene.
Reason: Prefer complex membership and adaptor/activator terms over a broad protein-binding annotation.
GO:0019899 enzyme binding
IEA
GO_REF:0000107 		KEEP AS NON CORE
Summary: Broad enzyme binding is plausible for an APH1A gamma-secretase subunit but is less informative than adaptor/activator and complex-membership annotations.
Reason: Retain as non-core because it may reflect real association with the presenilin protease but does not define APH1A primary molecular role.
GO:0061133 endopeptidase activator activity
IEA
GO_REF:0000107 		ACCEPT
Summary: APH1A is required for normal gamma-secretase assembly and activity, supporting an endopeptidase activator role at the complex level.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0005789 endoplasmic reticulum membrane
EXP
PMID:12522139
PEN-2 and APH-1 coordinately regulate proteolytic processing... 		ACCEPT
Summary: This membrane or endomembrane location is consistent with APH1A as a multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
Reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, Golgi, endosomal, and general membrane localizations are consistent with the curated biology.
GO:0005789 endoplasmic reticulum membrane
NAS
PMID:15274632
Purification and characterization of the human gamma-secreta... 		ACCEPT
Summary: This membrane or endomembrane location is consistent with APH1A as a multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
Reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, Golgi, endosomal, and general membrane localizations are consistent with the curated biology.
GO:0005886 plasma membrane
IDA
PMID:15274632
Purification and characterization of the human gamma-secreta... 		KEEP AS NON CORE
Summary: Plasma-membrane annotations are plausible for gamma-secretase substrate events, but APH1A-specific steady-state localization is strongest for ER and cis-Golgi membranes.
Reason: Retain as non-core because the site is biologically plausible for substrate processing without being the clearest APH1A-defining location.
GO:0007220 Notch receptor processing
NAS
PMID:10206645
A presenilin-1-dependent gamma-secretase-like protease media... 		ACCEPT
Summary: APH1A supports gamma-secretase-dependent Notch receptor processing and release of Notch intracellular domains.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0031293 membrane protein intracellular domain proteolysis
IDA
PMID:15274632
Purification and characterization of the human gamma-secreta... 		ACCEPT
Summary: This captures the core regulated intramembrane processing activity of the APH1A-containing gamma-secretase complex.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0042987 amyloid precursor protein catabolic process
IDA
PMID:15274632
Purification and characterization of the human gamma-secreta... 		ACCEPT
Summary: APH1A-containing gamma-secretase participates in APP processing that generates amyloid-beta-related products.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0070765 gamma-secretase complex
IPI
PMID:26280335
An atomic structure of human Ξ³-secretase. 		ACCEPT
Summary: APH1A is an established non-catalytic subunit of the gamma-secretase complex with presenilin, nicastrin, and PSENEN/PEN-2.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0000139 Golgi membrane
NAS
PMID:15274632
Purification and characterization of the human gamma-secreta... 		ACCEPT
Summary: This membrane or endomembrane location is consistent with APH1A as a multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
Reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, Golgi, endosomal, and general membrane localizations are consistent with the curated biology.
GO:0007220 Notch receptor processing
IMP
PMID:12297508
Mammalian APH-1 interacts with presenilin and nicastrin and ... 		ACCEPT
Summary: APH1A supports gamma-secretase-dependent Notch receptor processing and release of Notch intracellular domains.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0007220 Notch receptor processing
IDA
PMID:27608597
Specific combinations of presenilins and Aph1s affect the su... 		ACCEPT
Summary: APH1A supports gamma-secretase-dependent Notch receptor processing and release of Notch intracellular domains.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0016485 protein processing
IMP
PMID:12297508
Mammalian APH-1 interacts with presenilin and nicastrin and ... 		ACCEPT
Summary: This captures the core regulated intramembrane processing activity of the APH1A-containing gamma-secretase complex.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0016485 protein processing
IGI
PMID:12763021
APH1, PEN2, and Nicastrin increase Abeta levels and gamma-se... 		ACCEPT
Summary: This captures the core regulated intramembrane processing activity of the APH1A-containing gamma-secretase complex.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0016485 protein processing
IDA
PMID:27608597
Specific combinations of presenilins and Aph1s affect the su... 		ACCEPT
Summary: This captures the core regulated intramembrane processing activity of the APH1A-containing gamma-secretase complex.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0030674 protein-macromolecule adaptor activity
IMP
PMID:12297508
Mammalian APH-1 interacts with presenilin and nicastrin and ... 		ACCEPT
Summary: APH1A acts as a non-catalytic assembly/adaptor subunit that helps stabilize and organize active gamma-secretase complexes.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0034205 amyloid-beta formation
IMP
PMID:12297508
Mammalian APH-1 interacts with presenilin and nicastrin and ... 		ACCEPT
Summary: APH1A-containing gamma-secretase participates in APP processing that generates amyloid-beta-related products.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0034205 amyloid-beta formation
IGI
PMID:12763021
APH1, PEN2, and Nicastrin increase Abeta levels and gamma-se... 		ACCEPT
Summary: APH1A-containing gamma-secretase participates in APP processing that generates amyloid-beta-related products.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0034205 amyloid-beta formation
IDA
PMID:27608597
Specific combinations of presenilins and Aph1s affect the su... 		ACCEPT
Summary: APH1A-containing gamma-secretase participates in APP processing that generates amyloid-beta-related products.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0042987 amyloid precursor protein catabolic process
IGI
PMID:12763021
APH1, PEN2, and Nicastrin increase Abeta levels and gamma-se... 		ACCEPT
Summary: APH1A-containing gamma-secretase participates in APP processing that generates amyloid-beta-related products.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0042987 amyloid precursor protein catabolic process
IDA
PMID:27608597
Specific combinations of presenilins and Aph1s affect the su... 		ACCEPT
Summary: APH1A-containing gamma-secretase participates in APP processing that generates amyloid-beta-related products.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0061133 endopeptidase activator activity
IMP
PMID:12297508
Mammalian APH-1 interacts with presenilin and nicastrin and ... 		ACCEPT
Summary: APH1A is required for normal gamma-secretase assembly and activity, supporting an endopeptidase activator role at the complex level.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0061133 endopeptidase activator activity
IGI
PMID:12763021
APH1, PEN2, and Nicastrin increase Abeta levels and gamma-se... 		ACCEPT
Summary: APH1A is required for normal gamma-secretase assembly and activity, supporting an endopeptidase activator role at the complex level.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0070765 gamma-secretase complex
IDA
PMID:12297508
Mammalian APH-1 interacts with presenilin and nicastrin and ... 		ACCEPT
Summary: APH1A is an established non-catalytic subunit of the gamma-secretase complex with presenilin, nicastrin, and PSENEN/PEN-2.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0010008 endosome membrane
TAS
Reactome:R-HSA-9010096 		ACCEPT
Summary: This membrane or endomembrane location is consistent with APH1A as a multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
Reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, Golgi, endosomal, and general membrane localizations are consistent with the curated biology.
GO:0016020 membrane
IDA
PMID:25043039
Three-dimensional structure of human Ξ³-secretase. 		ACCEPT
Summary: This membrane or endomembrane location is consistent with APH1A as a multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
Reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, Golgi, endosomal, and general membrane localizations are consistent with the curated biology.
GO:0016020 membrane
IDA
PMID:26280335
An atomic structure of human Ξ³-secretase. 		ACCEPT
Summary: This membrane or endomembrane location is consistent with APH1A as a multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
Reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, Golgi, endosomal, and general membrane localizations are consistent with the curated biology.
GO:0034205 amyloid-beta formation
IMP
PMID:25043039
Three-dimensional structure of human Ξ³-secretase. 		ACCEPT
Summary: APH1A-containing gamma-secretase participates in APP processing that generates amyloid-beta-related products.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0034205 amyloid-beta formation
IMP
PMID:26280335
An atomic structure of human Ξ³-secretase. 		ACCEPT
Summary: APH1A-containing gamma-secretase participates in APP processing that generates amyloid-beta-related products.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0042982 amyloid precursor protein metabolic process
IDA
PMID:25043039
Three-dimensional structure of human Ξ³-secretase. 		ACCEPT
Summary: APH1A-containing gamma-secretase participates in APP processing that generates amyloid-beta-related products.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0042982 amyloid precursor protein metabolic process
IDA
PMID:26280335
An atomic structure of human Ξ³-secretase. 		ACCEPT
Summary: APH1A-containing gamma-secretase participates in APP processing that generates amyloid-beta-related products.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0070765 gamma-secretase complex
IDA
PMID:25043039
Three-dimensional structure of human Ξ³-secretase. 		ACCEPT
Summary: APH1A is an established non-catalytic subunit of the gamma-secretase complex with presenilin, nicastrin, and PSENEN/PEN-2.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0070765 gamma-secretase complex
IDA
PMID:26280335
An atomic structure of human Ξ³-secretase. 		ACCEPT
Summary: APH1A is an established non-catalytic subunit of the gamma-secretase complex with presenilin, nicastrin, and PSENEN/PEN-2.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0016020 membrane
HDA
PMID:19946888
Defining the membrane proteome of NK cells. 		ACCEPT
Summary: This membrane or endomembrane location is consistent with APH1A as a multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
Reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, Golgi, endosomal, and general membrane localizations are consistent with the curated biology.
GO:0005886 plasma membrane
TAS
Reactome:R-HSA-1251997 		KEEP AS NON CORE
Summary: Plasma-membrane annotations are plausible for gamma-secretase substrate events, but APH1A-specific steady-state localization is strongest for ER and cis-Golgi membranes.
Reason: Retain as non-core because the site is biologically plausible for substrate processing without being the clearest APH1A-defining location.
GO:0005886 plasma membrane
TAS
Reactome:R-HSA-193682 		KEEP AS NON CORE
Summary: Plasma-membrane annotations are plausible for gamma-secretase substrate events, but APH1A-specific steady-state localization is strongest for ER and cis-Golgi membranes.
Reason: Retain as non-core because the site is biologically plausible for substrate processing without being the clearest APH1A-defining location.
GO:0005886 plasma membrane
TAS
Reactome:R-HSA-205112 		KEEP AS NON CORE
Summary: Plasma-membrane annotations are plausible for gamma-secretase substrate events, but APH1A-specific steady-state localization is strongest for ER and cis-Golgi membranes.
Reason: Retain as non-core because the site is biologically plausible for substrate processing without being the clearest APH1A-defining location.
GO:0005886 plasma membrane
TAS
Reactome:R-HSA-2220988 		KEEP AS NON CORE
Summary: Plasma-membrane annotations are plausible for gamma-secretase substrate events, but APH1A-specific steady-state localization is strongest for ER and cis-Golgi membranes.
Reason: Retain as non-core because the site is biologically plausible for substrate processing without being the clearest APH1A-defining location.
GO:0005886 plasma membrane
TAS
Reactome:R-HSA-3928656 		KEEP AS NON CORE
Summary: Plasma-membrane annotations are plausible for gamma-secretase substrate events, but APH1A-specific steady-state localization is strongest for ER and cis-Golgi membranes.
Reason: Retain as non-core because the site is biologically plausible for substrate processing without being the clearest APH1A-defining location.
GO:0005886 plasma membrane
TAS
Reactome:R-HSA-9013361 		KEEP AS NON CORE
Summary: Plasma-membrane annotations are plausible for gamma-secretase substrate events, but APH1A-specific steady-state localization is strongest for ER and cis-Golgi membranes.
Reason: Retain as non-core because the site is biologically plausible for substrate processing without being the clearest APH1A-defining location.
GO:0005886 plasma membrane
TAS
Reactome:R-HSA-9017817 		KEEP AS NON CORE
Summary: Plasma-membrane annotations are plausible for gamma-secretase substrate events, but APH1A-specific steady-state localization is strongest for ER and cis-Golgi membranes.
Reason: Retain as non-core because the site is biologically plausible for substrate processing without being the clearest APH1A-defining location.
GO:0005886 plasma membrane
TAS
Reactome:R-HSA-9839376 		KEEP AS NON CORE
Summary: Plasma-membrane annotations are plausible for gamma-secretase substrate events, but APH1A-specific steady-state localization is strongest for ER and cis-Golgi membranes.
Reason: Retain as non-core because the site is biologically plausible for substrate processing without being the clearest APH1A-defining location.
GO:0005886 plasma membrane
TAS
Reactome:R-NUL-2197556 		KEEP AS NON CORE
Summary: Plasma-membrane annotations are plausible for gamma-secretase substrate events, but APH1A-specific steady-state localization is strongest for ER and cis-Golgi membranes.
Reason: Retain as non-core because the site is biologically plausible for substrate processing without being the clearest APH1A-defining location.
GO:0005886 plasma membrane
TAS
Reactome:R-NUL-9604300 		KEEP AS NON CORE
Summary: Plasma-membrane annotations are plausible for gamma-secretase substrate events, but APH1A-specific steady-state localization is strongest for ER and cis-Golgi membranes.
Reason: Retain as non-core because the site is biologically plausible for substrate processing without being the clearest APH1A-defining location.
GO:0031293 membrane protein intracellular domain proteolysis
IMP
PMID:12297508
Mammalian APH-1 interacts with presenilin and nicastrin and ... 		ACCEPT
Summary: This captures the core regulated intramembrane processing activity of the APH1A-containing gamma-secretase complex.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0042987 amyloid precursor protein catabolic process
IMP
PMID:12297508
Mammalian APH-1 interacts with presenilin and nicastrin and ... 		ACCEPT
Summary: APH1A-containing gamma-secretase participates in APP processing that generates amyloid-beta-related products.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0005783 endoplasmic reticulum
IDA
PMID:15274632
Purification and characterization of the human gamma-secreta... 		ACCEPT
Summary: This membrane or endomembrane location is consistent with APH1A as a multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
Reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, Golgi, endosomal, and general membrane localizations are consistent with the curated biology.
GO:0005794 Golgi apparatus
IDA
PMID:15274632
Purification and characterization of the human gamma-secreta... 		ACCEPT
Summary: This membrane or endomembrane location is consistent with APH1A as a multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
Reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, Golgi, endosomal, and general membrane localizations are consistent with the curated biology.
GO:0006509 membrane protein ectodomain proteolysis
IDA
PMID:15274632
Purification and characterization of the human gamma-secreta... 		MODIFY
Summary: Gamma-secretase acts after ectodomain shedding and performs intramembrane cleavage; ectodomain proteolysis is not the best APH1A process label.
Reason: Use an intramembrane substrate-processing term rather than ectodomain proteolysis for the APH1A-containing gamma-secretase complex.
GO:0007220 Notch receptor processing
TAS
PMID:15274632
Purification and characterization of the human gamma-secreta... 		ACCEPT
Summary: APH1A supports gamma-secretase-dependent Notch receptor processing and release of Notch intracellular domains.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0016485 protein processing
IDA
PMID:15274632
Purification and characterization of the human gamma-secreta... 		ACCEPT
Summary: This captures the core regulated intramembrane processing activity of the APH1A-containing gamma-secretase complex.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.
GO:0042987 amyloid precursor protein catabolic process
TAS
PMID:15274632
Purification and characterization of the human gamma-secreta... 		ACCEPT
Summary: APH1A-containing gamma-secretase participates in APP processing that generates amyloid-beta-related products.
Reason: The term aligns with APH1A function as a non-catalytic gamma-secretase subunit that supports complex assembly/activity and APP/Notch intramembrane processing.

Core Functions

APH1A is an essential non-catalytic gamma-secretase subunit that helps assemble and stabilize the APH1A-containing presenilin/nicastrin/PSENEN complex, enabling presenilin-dependent intramembrane cleavage of APP, Notch receptors, and related membrane substrates.

Molecular Function:
protein-macromolecule adaptor activity
Directly Involved In:
membrane protein intracellular domain proteolysis Notch receptor processing amyloid precursor protein catabolic process amyloid-beta formation protein processing
Cellular Locations:
endoplasmic reticulum membrane Golgi cisterna membrane Golgi membrane endosome membrane membrane
In Complex:
gamma-secretase complex
Supporting Evidence:
  • PMID:12297508
    physically associates with nicastrin and the heterodimers of the presenilin
  • PMID:12297508
    mAPH-1 is probably a functional component of the gamma-secretase complex required for the intramembrane proteolysis of APP and Notch
  • PMID:12763021
    APH1a, APH1b, PEN2, and Nicastrin proteins, which are part of the gamma-secretase complex with PS1
  • PMID:12763021
    these components are essential for gamma-secretase activity
  • PMID:25043039
    The Ξ³-secretase complex consists of four components: presenilin, Pen-2, Aph-1, and Nicastrin
  • PMID:25043039
    Cleavage of the substrate APP-C100 was blocked by the specific inhibitor III-31C
  • file:human/APH1A/APH1A-deep-research-falcon.md
    nicastrin (NCT) and APH1A first associate to form the initial subcomplex

References

GO_REF:0000002
Gene Ontology annotation through association of InterPro records with GO terms
GO_REF:0000033
Annotation inferences using phylogenetic trees
GO_REF:0000044
Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
GO_REF:0000107
Automatic transfer of experimentally verified manual GO annotation data to orthologs using Ensembl Compara
GO_REF:0000117
Electronic Gene Ontology annotations created by ARBA machine learning models
GO_REF:0000120
Combined Automated Annotation using Multiple IEA Methods
PMID:10206645
A presenilin-1-dependent gamma-secretase-like protease mediates release of Notch intracellular domain.
PMID:12297508
Mammalian APH-1 interacts with presenilin and nicastrin and is required for intramembrane proteolysis of amyloid-beta precursor protein and Notch.
PMID:12522139
PEN-2 and APH-1 coordinately regulate proteolytic processing of presenilin 1.
PMID:12763021
APH1, PEN2, and Nicastrin increase Abeta levels and gamma-secretase activity.
PMID:15274632
Purification and characterization of the human gamma-secretase complex.
PMID:18201567
Cellular localization of Nicastrin affects amyloid beta species production.
PMID:19376115
An alternative spliced mouse presenilin-2 mRNA encodes a novel gamma-secretase inhibitor.
PMID:19946888
Defining the membrane proteome of NK cells.
PMID:23864651
The identification of novel proteins that interact with the GLP-1 receptor and restrain its activity.
PMID:25043039
Three-dimensional structure of human Ξ³-secretase.
PMID:25394380
G206D Mutation of Presenilin-1 Reduces Pen2 Interaction, Increases AΞ²42/AΞ²40 Ratio and Elevates ER Ca(2+) Accumulation.
PMID:26280335
An atomic structure of human Ξ³-secretase.
PMID:27608597
Specific combinations of presenilins and Aph1s affect the substrate specificity and activity of Ξ³-secretase.
PMID:30559186
Bax inhibitor 1 is a Ξ³-secretase-independent presenilin-binding protein.
PMID:32296183
A reference map of the human binary protein interactome.
PMID:32814053
Interactome Mapping Provides a Network of Neurodegenerative Disease Proteins and Uncovers Widespread Protein Aggregation in Affected Brains.
Reactome:R-HSA-1251997
Cleavage of ERBB4m80 by gamma-scretase complex
Reactome:R-HSA-193682
gamma-secretase cleaves the p75NTR transmembrane domain
Reactome:R-HSA-205112
gamma-secretase cleaves p75NTR, releasing NRIF and TRAF6
Reactome:R-HSA-2220988
NEXT1 PEST domain mutants are cleaved to produce NICD1 PEST domain mutants
Reactome:R-HSA-3928656
gamma-secretase cleaves EPHB2
Reactome:R-HSA-9010096
Gamma-secretase cleaves APP(672-770) to APP(672-711) and APP(672-713)
Reactome:R-HSA-9013361
NEXT3 is cleaved to produce NICD3
Reactome:R-HSA-9017817
Gamma-secretase cleaves YBX1:NOTCH3
Reactome:R-HSA-9839376
TGFBR3(784-851) degradation
Reactome:R-NUL-2197556
Gamma-secretase complex cleaves mNEXT2
Reactome:R-NUL-9604300
Gamma-secretase cleaves Notch4
file:human/APH1A/APH1A-deep-research-falcon.md
Falcon deep research report for APH1A
  • Falcon corroborates the review's core framing of APH1A as a non-catalytic scaffold/assembly subunit that allosterically tunes gamma-secretase substrate processing rather than catalyzing cleavage itself.
    "APH1A also exerts allosteric effects on substrate processing, particularly influencing the processivity of sequential intramembrane cleavage."

Suggested Questions for Experts

Q: Which APH1A-containing gamma-secretase assemblies operate in ER/cis-Golgi compartments versus later endosomal or cell-surface substrate-processing compartments in human neural and glial cells?

Suggested experts: gamma-secretase complex experts, Notch and APP processing experts

Q: How should GO distinguish APH1A adaptor/assembly activity from APH1A contribution to presenilin catalytic activity within gamma-secretase?

Suggested experts: GO molecular-function curators, gamma-secretase structure-function experts

Suggested Experiments

Experiment: Compare endogenous APH1A and APH1B knockout or isoform-rescue human neural cells for APP, Notch, and other gamma-secretase substrate cleavage in ER/Golgi, endosomal, and plasma-membrane-enriched fractions.

Hypothesis: APH1A-containing complexes have compartment- and substrate-specific roles that are not fully captured by generic gamma-secretase annotations.

Type: endogenous isoform-rescue substrate-processing assay

Experiment: Introduce APH1A interface mutations in endogenous cells and quantify presenilin maturation, nicastrin association, complex abundance, and substrate-specific cleavage products.

Hypothesis: APH1A primarily controls gamma-secretase assembly/stability and substrate-processing competence rather than catalysis directly.

Type: complex assembly and activity assay

Deep Research

Falcon

(APH1A-deep-research-falcon.md)
Comprehensive Research Report: APH1A Gene Function and Annotation Falcon Edison Scientific Literature 13 citations 1 artifacts 2026-06-21T07:50:57.719531
Edison artifact artifact-00 (text/markdown)

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Comprehensive Research Report: APH1A Gene Function and Annotation

Gene Identity Verification

The gene APH1A (UniProt accession Q96BI3) encodes gamma-secretase subunit APH-1A (also known as Aph-1alpha or presenilin-stabilization factor) in humans (strooper2024newprecisionmedicine pages 1-2, ning2025themanipulatorbehind pages 2-4). This identity has been confirmed across multiple authoritative reviews and structural studies from 2023-2026 (odorcic2024apoandaΞ²46bound pages 1-2, malvankar2026theΞ³secretasecomplex pages 1-4, ning2025themanipulatorbehind pages 2-4). APH1A belongs to the APH-1 family and is one of two human APH-1 paralogs (APH1A and APH1B) that combine with two presenilin isoforms (PSEN1/2), nicastrin (NCT), and presenilin enhancer-2 (PEN-2/PSENEN) to generate four distinct gamma-secretase complexes in human cells (strooper2024newprecisionmedicine pages 1-2, strooper2024newprecisionmedicine pages 3-4).

Primary Molecular Function

Structural Role in Gamma-Secretase Complex

APH1A is a non-catalytic scaffold protein essential for the assembly, maturation, and stabilization of the gamma-secretase complex (malvankar2026theΞ³secretasecomplex pages 6-9, ning2025themanipulatorbehind pages 2-4). The protein consists of seven transmembrane domains (TMDs), with the N-terminus facing the extracellular/luminal side and the C-terminus facing the cytosol (malvankar2026theΞ³secretasecomplex pages 6-9, odorcic2024apoandaΞ²46bound pages 4-5). This transmembrane architecture positions APH1A as a central structural component of the membrane-embedded protease complex.

Recent cryo-EM structural studies from 2024 have elucidated the molecular details of APH1A's interactions within the gamma-secretase complex. APH1A establishes a major interface with presenilin (PSEN1) spanning approximately 2,000 Γ…Β², involving APH-1 transmembrane helices TM2-TM4 contacting PSEN1 TM1 and TM8-TM9 (odorcic2024apoandaΞ²46bound pages 2-4, odorcic2024apoandaΞ²46bound pages 4-5). Additionally, the C-terminus of PSEN1 inserts into the APH-1 helical bundle on the extracellular side (odorcic2024apoandaΞ²46bound pages 2-4). These extensive interactions provide the structural basis for APH1A's historical designation as a "presenilin-stabilization factor."

Complex Assembly Process

APH1A plays a central role in the stepwise assembly of the gamma-secretase complex, which occurs through the following sequence (malvankar2026theΞ³secretasecomplex pages 6-9, ning2025themanipulatorbehind pages 2-4):

  1. Initial subcomplex formation: In the endoplasmic reticulum (ER), nicastrin (NCT) and APH1A first associate to form the initial subcomplex (malvankar2026theΞ³secretasecomplex pages 6-9, ning2025themanipulatorbehind pages 2-4).

  2. Presenilin recruitment: The NCT-APH1A subcomplex then recruits full-length presenilin (PSEN1 or PSEN2), forming a trimeric intermediate (malvankar2026theΞ³secretasecomplex pages 6-9, ning2025themanipulatorbehind pages 2-4).

  3. PEN-2 binding and activation: PEN-2/PSENEN subsequently binds, particularly interacting with PSEN transmembrane domain 4 (TMD4), which triggers presenilin autoproteolysis between TM6 and TM7, generating stable N-terminal (NTF) and C-terminal (CTF) fragments (malvankar2026theΞ³secretasecomplex pages 6-9, ning2025themanipulatorbehind pages 2-4).

  4. Maturation in Golgi: The assembled complex matures in the Golgi apparatus, where nicastrin undergoes full glycosylation, before trafficking to its functional destinations (strooper2024newprecisionmedicine pages 3-4, malvankar2026theΞ³secretasecomplex pages 6-9).

This ordered assembly process explains why APH1A is absolutely essential for gamma-secretase functionβ€”without APH1A, presenilin cannot be properly incorporated and activated within a functional complex.

Modulation of Catalytic Activity

While APH1A itself is not catalytic (the active site contains two aspartate residues, Asp257 and Asp385, located in PSEN1 TM6 and TM7), it significantly influences the enzyme's proteolytic properties through allosteric mechanisms (malvankar2026theΞ³secretasecomplex pages 6-9, strooper2024newprecisionmedicine pages 5-6). Structural studies from 2024 reveal that substrate binding induces concerted conformational rearrangements at the PSEN1/APH-1 interface, particularly involving the APH-1 TM3-TM4 loop region (odorcic2024apoandaΞ²46bound pages 1-2, odorcic2024apoandaΞ²46bound pages 5-7). This allosteric pathway connects substrate occupancy in the active site with structural changes propagating through PSEN1 TM1 and TM8-9 to the APH-1 interface (odorcic2024apoandaΞ²46bound pages 1-2, odorcic2024apoandaΞ²46bound pages 5-7).

Importantly, APH1A-containing gamma-secretase complexes differ functionally from APH1B-containing complexes. Complexes with PSEN1 and APH1A exhibit greater substrate processivity, producing relatively more short amyloid-Ξ² (AΞ²) peptides compared to complexes containing PSEN2 and/or APH1B, which generate more long, aggregation-prone AΞ² species (AΞ²42, AΞ²43) (odorcic2024apoandaΞ²46bound pages 1-2, strooper2024newprecisionmedicine pages 6-7). This functional difference has profound implications for Alzheimer's disease pathogenesis, as longer AΞ² peptides are more prone to form toxic oligomers and amyloid plaques.

Substrate Processing and Enzymatic Mechanism

Substrate Specificity

Gamma-secretase complexes containing APH1A cleave type I transmembrane proteins with short ectodomains, typically after their large extracellular domains have been removed by other proteases (ectodomain shedding) (odorcic2024apoandaΞ²46bound pages 1-2, hou2023theΞ³secretasesubstrate pages 1-4, malvankar2026theΞ³secretasecomplex pages 11-15). The enzyme exhibits remarkable substrate promiscuity, processing more than 145-150 different membrane proteins (hou2023theΞ³secretasesubstrate pages 1-4, hou2023theΞ³secretasesubstrate pages 4-6, malvankar2026theΞ³secretasecomplex pages 11-15). A 2023 unbiased substrate screen in human microglia identified 85 gamma-secretase substrates, including 59 not previously recognized, demonstrating the extensive reach of this proteolytic system (hou2023theΞ³secretasesubstrate pages 1-4, hou2023theΞ³secretasesubstrate pages 4-6).

Key Substrates and Processing Mechanisms

Amyloid Precursor Protein (APP):

The processing of APP represents the most intensively studied gamma-secretase substrate, particularly due to its central role in Alzheimer's disease. After Ξ²-secretase (BACE1) cleaves APP to generate the 99-amino acid C-terminal fragment (C99), gamma-secretase performs sequential intramembrane cleavage (strooper2024newprecisionmedicine pages 5-6, strooper2024newprecisionmedicine pages 4-5, vilyaninov2024Ξ³secretaseinthe pages 3-6, malvankar2026theΞ³secretasecomplex pages 15-17):

  1. Epsilon (Ξ΅) cleavage: The initial endoproteolytic cut occurs near the cytosolic side of the membrane, releasing the APP intracellular domain (AICD) into the cytoplasm (strooper2024newprecisionmedicine pages 5-6, malvankar2026theΞ³secretasecomplex pages 15-17).

  2. Sequential trimming: The remaining membrane-bound fragment undergoes progressive carboxypeptidase-like cleavages, removing 3-4 amino acids per step. This sequential processing generates two major product lines:

  3. AΞ²49β†’46β†’43β†’40β†’37 (the predominant pathway)
  4. AΞ²48β†’45β†’42β†’38 (producing the more aggregation-prone AΞ²42)
    (strooper2024newprecisionmedicine pages 5-6, strooper2024newprecisionmedicine pages 4-5, vilyaninov2024Ξ³secretaseinthe pages 3-6)

Recent structural studies reveal that during this process, the substrate's transmembrane helix progressively unwinds within the gamma-secretase catalytic chamber, with each cleavage step requiring reformation of a stabilizing Ξ²-sheet interaction between the substrate C-terminus and PSEN1 Ξ²-strands (strooper2024newprecisionmedicine pages 5-6, strooper2024newprecisionmedicine pages 4-5). APH1A influences this processivity through its allosteric effects on the enzyme-substrate complex stability.

Notch Receptors:

Notch signaling represents the second major gamma-secretase pathway. After ligand binding and ADAM10-mediated S2 cleavage generate the Notch extracellular truncation (NEXT), gamma-secretase performs the critical S3 cleavage within the membrane, releasing the Notch intracellular domain (NICD) into the cytosol (strooper2024newprecisionmedicine pages 1-2, malvankar2026theΞ³secretasecomplex pages 15-17). NICD then translocates to the nucleus where it activates transcription of Notch target genes critical for development and cell fate determination (malvankar2026theΞ³secretasecomplex pages 15-17). The membrane-bound remnant (NΞ²) undergoes further trimming by gamma-secretase at S4 sites, similar to the sequential processing of APP (malvankar2026theΞ³secretasecomplex pages 15-17).

Broader Substrate Repertoire:

Beyond APP and Notch, gamma-secretase processes numerous other substrates involved in diverse cellular processes. The 2023 microglia substrate screen identified substrates including CSF1R (critical for microglial survival), TREM2 (implicated in Alzheimer's disease risk), and multiple cytokine receptors and adhesion molecules (hou2023theΞ³secretasesubstrate pages 1-4, hou2023theΞ³secretasesubstrate pages 4-6). This breadth of substrates positions APH1A-containing gamma-secretase as a central hub for regulated intramembrane proteolysis (RIP), coordinating multiple signaling pathways through irreversible proteolytic events (hou2023theΞ³secretasesubstrate pages 1-4).

Subcellular Localization

Biosynthesis and Trafficking

APH1A follows a defined intracellular trafficking route as part of the gamma-secretase complex biogenesis pathway:

  1. Endoplasmic Reticulum: Initial assembly with nicastrin occurs in the ER membrane (strooper2024newprecisionmedicine pages 3-4, malvankar2026theΞ³secretasecomplex pages 6-9, ning2025themanipulatorbehind pages 2-4).

  2. Golgi Apparatus: The complex matures in the Golgi, where nicastrin undergoes glycosylation and presenilin autoproteolysis is completed (strooper2024newprecisionmedicine pages 3-4, malvankar2026theΞ³secretasecomplex pages 6-9).

  3. Secretory Pathway: Mature complexes traffic through the secretory pathway to reach functional destinations (strooper2024newprecisionmedicine pages 3-4, malvankar2026theΞ³secretasecomplex pages 6-9).

Sites of Functional Activity

APH1A-containing gamma-secretase complexes are functionally active at multiple subcellular locations (strooper2024newprecisionmedicine pages 3-4, malvankar2026theΞ³secretasecomplex pages 6-9):

  • Plasma Membrane: The cell surface represents a major site of gamma-secretase activity, where substrate cleavage occurs following ectodomain shedding by cell-surface proteases (strooper2024newprecisionmedicine pages 3-4, malvankar2026theΞ³secretasecomplex pages 6-9).

  • Endosomal System: Complexes containing PSEN1 (which frequently pair with APH1A) cycle between the cell surface and endosomes, with significant proteolytic activity in the endosomal compartment (strooper2024newprecisionmedicine pages 3-4).

  • Late Endosomes/Lysosomes: Some gamma-secretase activity occurs in late endosomal and lysosomal compartments, though PSEN2-containing complexes are more enriched in these locations (strooper2024newprecisionmedicine pages 3-4).

This multi-compartmental localization enables gamma-secretase to encounter and process substrates at various stages of their trafficking through the secretory and endocytic pathways, explaining the diverse substrate repertoire.

Biological Pathways and Signaling Networks

Notch Signaling Pathway

The most critical developmental role of APH1A is in Notch signaling, a highly conserved pathway controlling cell fate decisions, proliferation, and differentiation (strooper2024newprecisionmedicine pages 1-2, malvankar2026theΞ³secretasecomplex pages 15-17). Genetic evidence strongly supports this function: knockout of Aph1a in mice causes lethal Notch phenotypes during embryogenesis, whereas Aph1b knockout results in only mild behavioral deficits in adulthood (strooper2024newprecisionmedicine pages 3-4). This demonstrates that APH1A is the predominant APH-1 paralog essential for canonical developmental Notch signaling.

Amyloid-Ξ² Processing and Alzheimer's Disease

In Alzheimer's disease pathogenesis, the specific composition of gamma-secretase complexes critically determines the length distribution of AΞ² peptides produced. Recent work (2023-2024) has established that APH1A-containing complexes, particularly PSEN1/APH1A combinations, exhibit greater processivity in sequential AΞ² trimming, favoring production of shorter, less aggregation-prone AΞ² species (AΞ²37, AΞ²38, AΞ²40) over longer pathogenic forms (AΞ²42, AΞ²43) (odorcic2024apoandaΞ²46bound pages 1-2, strooper2024newprecisionmedicine pages 6-7).

A landmark 2022 study demonstrated a linear correlation (RΒ² = 0.78, p < 0.0001) between the ratio of short-to-long AΞ² peptides and age of onset in familial Alzheimer's disease patients carrying PSEN1 mutations (strooper2024newprecisionmedicine pages 4-5). This finding supports a model where destabilization of the enzyme-substrate complex (as occurs with pathogenic PSEN mutations) leads to premature release of incompletely processed, longer AΞ² species that seed amyloid aggregation (strooper2024newprecisionmedicine pages 5-6, strooper2024newprecisionmedicine pages 4-5). By extension, APH1A's role in stabilizing the complex and promoting processivity represents a protective influence against Alzheimer's pathogenesis.

Regulated Intramembrane Proteolysis Network

Beyond these two major pathways, APH1A functions within a broad regulated intramembrane proteolysis (RIP) signaling network (hou2023theΞ³secretasesubstrate pages 1-4). The diverse substrate repertoire encompasses proteins involved in:

  • Immune signaling: Cytokine and pattern recognition receptors in microglia and immune cells
  • Cell adhesion and migration: Cadherins and integrins
  • Receptor tyrosine kinase signaling: Growth factor receptors
  • Apoptosis and cell survival: Death receptors and survival factor receptors
    (hou2023theΞ³secretasesubstrate pages 1-4, hou2023theΞ³secretasesubstrate pages 4-6)

This network architecture positions gamma-secretase as a "signaling hub" that integrates extracellular cues into coordinated intracellular transcriptional responses through release of multiple intracellular domains (hou2023theΞ³secretasesubstrate pages 1-4).

Recent Developments (2023-2026)

Structural Insights from Cryo-EM

The most significant recent advance is the 2024 publication of cryo-EM structures of gamma-secretase complexes containing APH-1B bound to the intermediate substrate AΞ²46, without cross-linking (odorcic2024apoandaΞ²46bound pages 1-2, odorcic2024apoandaΞ²46bound pages 5-7). These structures, resolved at 3.3 Γ… for the apo complex and with substrate-bound forms, reveal:

  1. Isoform-specific structural differences: Three non-conserved regions in APH-1 (including the TM3-TM4 loop) establish distinct contacts with PSEN1 (odorcic2024apoandaΞ²46bound pages 1-2, odorcic2024apoandaΞ²46bound pages 4-5).

  2. Allosteric coupling mechanism: Substrate binding induces concerted rearrangements at the PSEN1/APH-1 interface, providing structural evidence for APH-1's allosteric modulation of substrate processing (odorcic2024apoandaΞ²46bound pages 1-2, odorcic2024apoandaΞ²46bound pages 5-7).

  3. Substrate recognition determinants: New hydrogen bonding interactions between loop 1 of PSEN1 (including Tyr115) and the substrate backbone contribute to substrate stabilization during sequential cleavage (odorcic2024apoandaΞ²46bound pages 5-7).

These structural insights, while obtained with APH-1B, are directly informative for understanding APH1A function through comparative analysis, as APH1A-containing complexes served as the reference structures (odorcic2024apoandaΞ²46bound pages 1-2, odorcic2024apoandaΞ²46bound pages 2-4).

Unbiased Substrate Discovery

A 2023 study introduced the G-SECSI (gamma-secretase substrate identification) method, an unbiased mass spectrometry approach that identified 85 substrates in human microglia, with 59 not previously known to be gamma-secretase substrates (hou2023theΞ³secretasesubstrate pages 1-4, hou2023theΞ³secretasesubstrate pages 4-6). This work revealed that gamma-secretase processes substrates in parallel rather than sequentially, and that many substrates are involved in defining distinct microglial cell states in both homeostatic and disease conditions (hou2023theΞ³secretasesubstrate pages 1-4). This has important implications for understanding gamma-secretase inhibitor toxicities and for developing more targeted therapeutic approaches.

Therapeutic Implications and Gamma-Secretase Modulators

Recent reviews (2024-2026) have refined the concept of "gamma-secretase modulators" (GSMs) to distinguish a newer class of compounds termed "gamma-secretase allosteric stabilizers" (GSAS) (strooper2024newprecisionmedicine pages 6-7). Unlike earlier GSMs that primarily reduced AΞ²42, GSAS compounds stabilize the enzyme-substrate complex to increase overall processivity, shifting the entire AΞ² product spectrum toward shorter peptides (strooper2024newprecisionmedicine pages 6-7). This mechanism mimics the natural function of APH1A-containing complexes and acts opposite to familial Alzheimer's disease mutations.

Understanding APH1A's contribution to complex-specific properties has practical therapeutic importance: some compounds show preferential activity against APH1B- versus APH1A-containing complexes (strooper2024newprecisionmedicine pages 2-3, strooper2024newprecisionmedicine pages 6-7). Developing complex-selective inhibitors or modulators could enable targeting of specific gamma-secretase functions (e.g., in cancer) while sparing essential activities (e.g., Notch signaling), addressing the mechanism-based toxicities that have plagued broad-spectrum gamma-secretase inhibitors in clinical trials (strooper2024newprecisionmedicine pages 1-2, strooper2024newprecisionmedicine pages 2-3, strooper2024newprecisionmedicine pages 6-7).

Current Applications and Expert Perspectives

Biomedical Research Applications

APH1A research currently focuses on several applications:

  1. Alzheimer's disease therapeutics: Understanding how APH1A influences AΞ² processivity guides development of GSAS compounds for Alzheimer's prevention (strooper2024newprecisionmedicine pages 6-7).

  2. Cancer therapeutics: The first gamma-secretase inhibitor (nirogacestat/Ogsiveo) received FDA approval in 2023 for desmoid tumors, validating gamma-secretase as a cancer target (strooper2024newprecisionmedicine pages 2-3). APH1A-selective approaches may enable safer cancer therapies.

  3. Developmental biology: APH1A serves as a critical tool for dissecting Notch signaling mechanisms in embryonic development and tissue homeostasis (strooper2024newprecisionmedicine pages 3-4).

Expert Consensus and Open Questions

Leading researchers in the field (De Strooper, Karran, Wolfe, and others) emphasize several key points in recent authoritative reviews (strooper2024newprecisionmedicine pages 1-2, strooper2024newprecisionmedicine pages 3-4, malvankar2026theΞ³secretasecomplex pages 1-4, strooper2024newprecisionmedicine pages 6-7):

  1. Complexity of gamma-secretase biology: The existence of four human gamma-secretase complexes with distinct tissue distributions, subcellular localizations, and substrate preferences creates both therapeutic challenges and opportunities for selective targeting (strooper2024newprecisionmedicine pages 1-2, strooper2024newprecisionmedicine pages 3-4).

  2. Amyloid cascade refinement: Recent evidence supports that the ratio of short-to-long AΞ² peptides, rather than absolute AΞ²42 levels alone, determines Alzheimer's disease risk and age of onset (strooper2024newprecisionmedicine pages 5-6, strooper2024newprecisionmedicine pages 4-5). This refines the amyloid hypothesis and validates APH1A's processivity-enhancing function as protective.

  3. Need for complex-selective tools: The field recognizes that broad gamma-secretase inhibition causes unacceptable Notch-related toxicities; future therapeutics must achieve selectivity, potentially by targeting APH1A/B isoform differences or complex-specific regulatory proteins (strooper2024newprecisionmedicine pages 1-2, strooper2024newprecisionmedicine pages 6-7).

Recent Statistical Data and Clinical Relevance

  • Substrate repertoire: >150 gamma-secretase substrates identified across studies (malvankar2026theΞ³secretasecomplex pages 11-15)
  • Microglial substrates: 85 substrates identified in 2023 microglia screen, 69% newly discovered (hou2023theΞ³secretasesubstrate pages 1-4, hou2023theΞ³secretasesubstrate pages 4-6)
  • Alzheimer's correlation: Age of onset correlates with short/long AΞ² ratio (RΒ² = 0.78, p < 0.0001) in PSEN1 mutation carriers (strooper2024newprecisionmedicine pages 4-5)
  • Familial mutations: >300 PSEN1 mutations identified as causing familial Alzheimer's disease, but no disease-causing mutations in APH1A itself (strooper2024newprecisionmedicine pages 3-4, ning2025themanipulatorbehind pages 2-4)

Summary

APH1A encodes a seven-transmembrane domain scaffold protein that is essential for gamma-secretase complex assembly, stability, and function. Its primary role is structural rather than catalyticβ€”APH1A stabilizes presenilin and enables formation of the active protease complex. However, recent structural and functional studies reveal that APH1A also exerts allosteric effects on substrate processing, particularly influencing the processivity of sequential intramembrane cleavage. APH1A-containing complexes favor production of shorter AΞ² peptides, conferring a protective influence against Alzheimer's disease pathogenesis. The protein functions at multiple subcellular locations (plasma membrane, endosomes) where it participates in processing >150 type I transmembrane substrates, including the critical APP and Notch proteins. Recent cryo-EM structures (2024) have illuminated the molecular basis of APH1A's effects through detailed characterization of PSEN1/APH-1 interfaces and substrate-induced conformational changes. Understanding APH1A's structure-function relationships continues to guide development of safer, more selective gamma-secretase therapeutics for Alzheimer's disease and cancer.

Feature area APH1A-specific finding Evidence/details Main implications Key citation(s)
Identity verified APH1A is the human gamma-secretase subunit APH-1A (Anterior pharynx-defective 1A), one of the two human APH-1 isoforms in the heterotetrameric gamma-secretase complex Recent reviews and structural papers consistently describe four human gamma-secretase complexes generated by combinations of PSEN1/2 with APH1A/B, plus NCSTN and PSENEN/PEN-2 Confirms the target is the human gamma-secretase scaffold subunit, not an unrelated gene symbol (odorcic2024apoandaΞ²46bound pages 1-2, strooper2024newprecisionmedicine pages 3-4, malvankar2026theΞ³secretasecomplex pages 6-9)
Molecular class / primary role APH1A is a non-catalytic, multi-pass membrane scaffold/stabilizer required for assembly and maturation of gamma-secretase APH-1 is described as stabilizing the enzyme complex and serving as a scaffold for assembly; presenilin only becomes active after incorporation into the full complex APH1A does not catalyze peptide bond hydrolysis itself; instead it enables formation and function of the active protease complex (malvankar2026theΞ³secretasecomplex pages 6-9, ning2025themanipulatorbehind pages 2-4)
Membrane topology APH1A is a 7-transmembrane-domain protein Sequence/topology summaries in recent reviews assign APH-1 seven TMDs, with N-terminus facing the extracellular/luminal side and C-terminus facing cytosol Topology is consistent with a structural role in the membrane-embedded core of gamma-secretase (malvankar2026theΞ³secretasecomplex pages 6-9, odorcic2024apoandaΞ²46bound pages 4-5)
Key structural interfaces APH1A forms a major membrane-embedded interface with presenilin involving APH-1 TM2-TM4 contacting PSEN1 TM1 and TM8-TM9, with insertion of the PSEN1 C-terminus into the APH-1 helical bundle on the extracellular side The 2024 cryo-EM APH-1B study defines the conserved PSEN1/APH-1 interface and shows that isoform-specific APH-1 regions contact PSEN1 across an interface of ~2000 Γ…Β²; these data are informative for APH1A because the APH1A-bound complex is the comparison reference Provides a structural basis for APH1A as the presenilin-stabilizing factor and as a regulator of presenilin conformational dynamics (odorcic2024apoandaΞ²46bound pages 2-4, odorcic2024apoandaΞ²46bound pages 4-5, odorcic2024apoandaΞ²46bound pages 5-7)
Isoform-specific structural determinants Relative to APH-1B, APH-1A differs in three non-conserved structural regions, including the TM3-TM4 loop, which is implicated in substrate-induced conformational coupling The 2024 cryo-EM comparison shows APH-1 isoform divergence clusters in specific regions and that substrate binding propagates conformational change toward the PSEN1/APH-1 interface Supports the idea that APH1A is not just passive scaffold but helps tune gamma-secretase conformational states and product profiles (odorcic2024apoandaΞ²46bound pages 1-2, odorcic2024apoandaΞ²46bound pages 4-5, odorcic2024apoandaΞ²46bound pages 5-7)
Complex assembly step 1 Nicastrin (NCSTN) and APH1A first form an early subcomplex in the endoplasmic reticulum Multiple reviews describe stepwise assembly beginning with NCSTN-APH-1 association in ER membranes APH1A nucleates early assembly of gamma-secretase biogenesis (strooper2024newprecisionmedicine pages 3-4, malvankar2026theΞ³secretasecomplex pages 6-9, ning2025themanipulatorbehind pages 2-4)
Complex assembly step 2 The NCSTN-APH1A subcomplex recruits full-length presenilin Presenilin joins the APH-1/NCT subcomplex before PEN-2 addition Explains the historical alias β€œpresenilin-stabilization factor” and APH1A’s central role in presenilin maturation (malvankar2026theΞ³secretasecomplex pages 6-9, ning2025themanipulatorbehind pages 2-4)
Complex assembly step 3 PEN-2/PSENEN then binds, especially via PSEN1 TMD4, triggering presenilin autoproteolysis into NTF and CTF Reviews summarize PEN-2-dependent activation after APH-1/NCT/presenilin preassembly APH1A supports formation of the proenzyme whose maturation yields the active gamma-secretase complex (malvankar2026theΞ³secretasecomplex pages 6-9, strooper2024newprecisionmedicine pages 3-4)
Post-assembly maturation Full complex matures in the Golgi, where nicastrin becomes fully glycosylated, before onward trafficking Recent review summarizes ER dimer formation and Golgi completion/maturation Places APH1A function in the secretory pathway during biogenesis as well as later in active complexes (strooper2024newprecisionmedicine pages 3-4, malvankar2026theΞ³secretasecomplex pages 6-9)
Contribution to catalysis APH1A is not the catalytic subunit; catalysis occurs at PSEN1 Asp257/Asp385 within the active site Structural reviews place the catalytic aspartates in PSEN TM6 and TM7, with APH-1 acting as a supporting subunit APH1A affects proteolysis indirectly through complex architecture, substrate gating, and stabilization (malvankar2026theΞ³secretasecomplex pages 6-9, strooper2024newprecisionmedicine pages 5-6)
Contribution to substrate processing APH-1 isoforms modulate substrate processivity and the length distribution of AΞ² peptides produced from APP 2024 structural work and recent reviews note that complexes containing PSEN2 and/or APH-1B generate relatively more long, aggregation-prone AΞ² species than complexes with PSEN1 and/or APH-1A By inference, APH1A-containing complexes are associated with comparatively greater processive trimming toward shorter AΞ² products (odorcic2024apoandaΞ²46bound pages 1-2, strooper2024newprecisionmedicine pages 6-7)
Allosteric regulation APH1A likely contributes to allosteric-like coupling between substrate binding and conformational changes in presenilin The 2024 cryo-EM APH-1B/AΞ²46 study shows substrate-induced rearrangements at the PSEN1/APH-1 interface and proposes an allosteric pathway connecting PSEN1 TM1/TM8-9 to the APH-1 TM3-TM4 loop; APH1A is the key comparator in these analyses Strongest recent mechanistic evidence that APH1A-family proteins modulate gamma-secretase activity beyond simple assembly (odorcic2024apoandaΞ²46bound pages 1-2, odorcic2024apoandaΞ²46bound pages 5-7)
Substrate class Gamma-secretase complexes containing APH1A cleave type I transmembrane proteins, typically after ectodomain shedding and when the residual ectodomain is short Recent reviews emphasize lack of strict sequence consensus but a common requirement for type I membrane topology and short ectodomains Defines the biochemical context in which APH1A functions (odorcic2024apoandaΞ²46bound pages 1-2, hou2023theΞ³secretasesubstrate pages 1-4, malvankar2026theΞ³secretasecomplex pages 11-15)
APP processing pathway In APP processing, gamma-secretase first performs epsilon cleavage near the cytosolic leaflet to release AICD, then sequentially trims membrane-retained AΞ² intermediates to shorter AΞ² species Recent reviews summarize the AΞ²49β†’46β†’43β†’40β†’37 and AΞ²48β†’45β†’42β†’38 trimming lines APH1A’s functional importance lies in shaping processivity of this sequential intramembrane trimming reaction (strooper2024newprecisionmedicine pages 5-6, strooper2024newprecisionmedicine pages 4-5, vilyaninov2024Ξ³secretaseinthe pages 3-6)
Notch pathway role Gamma-secretase containing APH1A cleaves Notch after ADAM-mediated S2 cleavage, releasing NICD into the cytosol/nucleus Notch is one of the best-established substrates and a central signaling readout of gamma-secretase function Explains why APH1A loss has strong developmental consequences and why broad gamma-secretase inhibition causes Notch-related toxicity (strooper2024newprecisionmedicine pages 1-2, malvankar2026theΞ³secretasecomplex pages 15-17)
Breadth of substrate proteome Gamma-secretase processes more than 145-150 substrates; a 2023 unbiased microglial substrate screen identified 85 substrates, including 59 not previously known in that context Hou et al. developed G-SECSI and showed extensive parallel processing in human microglia APH1A participates in a broad regulated intramembrane proteolysis network rather than a single-pathway enzyme system (hou2023theΞ³secretasesubstrate pages 1-4, hou2023theΞ³secretasesubstrate pages 4-6, malvankar2026theΞ³secretasecomplex pages 11-15)
Subcellular localization of active function APH1A functions in gamma-secretase complexes located in the plasma membrane and endosomal system after assembly in the ER/Golgi pathway Reviews place mature complexes at the cell surface, endosomes, and lysosomes; super-resolution imaging confirms cell-surface gamma-secretase organization and dynamics APH1A acts where membrane stubs of substrates encounter active gamma-secretase for intramembrane cleavage (strooper2024newprecisionmedicine pages 3-4, malvankar2026theΞ³secretasecomplex pages 6-9)
Complex-specific trafficking context Complexes containing PSEN1 are recycled between the cell surface and endosomes, whereas PSEN2 complexes are targeted more to late endosomes/lysosomes De Strooper & Karran summarize compartmental differences among gamma-secretase complexes APH1A localization depends partly on its presenilin partner; APH1A frequently participates in PSEN1 complexes with surface/endosomal activity (strooper2024newprecisionmedicine pages 3-4)
Disease relevance: development Aph1a knockout causes lethal Notch phenotypes during embryogenesis, unlike the milder phenotype of Aph1b loss Recent review contrasts knockout phenotypes of APH1 paralogs Indicates APH1A is the more essential APH-1 paralog for canonical developmental Notch signaling (strooper2024newprecisionmedicine pages 3-4)
Disease relevance: Alzheimer’s disease APH1A influences AΞ² peptide length distribution, a core determinant of Alzheimer’s disease pathobiology, though AD-causing familial mutations are mainly in PSEN1/2, not APH1A 2024 reviews emphasize that longer AΞ² species seed aggregation; isoform composition of gamma-secretase contributes to AΞ²-length bias APH1A is mechanistically relevant to AD through complex composition and processivity, rather than as a common Mendelian AD mutation gene (odorcic2024apoandaΞ²46bound pages 1-2, strooper2024newprecisionmedicine pages 4-5, strooper2024newprecisionmedicine pages 6-7)
Disease relevance: hidradenitis suppurativa and skin inflammation Classical loss-of-function mutations in gamma-secretase subunits causing hidradenitis suppurativa have mostly been found in NCSTN and PSENEN, though recent dermatology reviews mention proposed APH1A/APH1B variants Reviews distinguish AD-causing PSEN mutations from gamma-secretase haploinsufficiency syndromes affecting skin/Notch biology Suggests APH1A may contribute to skin disease when gamma-secretase dosage/function is perturbed, but evidence is much weaker than for NCSTN/PSENEN (strooper2024newprecisionmedicine pages 3-4, ning2025themanipulatorbehind pages 2-4)
Disease relevance: pharmacology / oncology Broad gamma-secretase inhibition causes mechanism-based toxicities, but selective targeting of specific complexes is an active therapeutic goal in cancer and AD prevention research Recent reviews note first GSI approval (nirogacestat) and discuss the need for complex-selective inhibitors/modulators; some compounds show relative selectivity for APH1B- vs APH1A-containing complexes APH1A is a practical pharmacology discriminator for designing safer, complex-selective gamma-secretase therapeutics (strooper2024newprecisionmedicine pages 2-3, strooper2024newprecisionmedicine pages 6-7)

Table: This table compiles the main structural, mechanistic, localization, and disease-relevant features of human APH1A as a gamma-secretase subunit. It emphasizes recent cryo-EM and functional evidence, especially how APH1A supports assembly and modulates substrate processing.

References

  1. (strooper2024newprecisionmedicine pages 1-2): Bart de Strooper and Eric H. Karran. New precision medicine avenues to the prevention of alzheimer’s disease from insights into the structure and function of Ξ³-secretases. The EMBO Journal, 43(6):887-903, Feb 2024. URL: https://doi.org/10.1038/s44318-024-00057-w, doi:10.1038/s44318-024-00057-w. This article has 40 citations.

  2. (ning2025themanipulatorbehind pages 2-4): Gao Ning, Xing Fan, Du Juan, Zhao wenxue, Wang Sijia, Chen Meinei, Dong Xiaolong, and Qi Yiming. The manipulator behind β€œscissors”: Ξ³ -secretase and its modulators in alzheimer’s disease. Frontiers in Aging Neuroscience, Aug 2025. URL: https://doi.org/10.3389/fnagi.2025.1637671, doi:10.3389/fnagi.2025.1637671. This article has 4 citations and is from a peer-reviewed journal.

  3. (odorcic2024apoandaΞ²46bound pages 1-2): Ivica OdorčiΔ‡, Mohamed Belal Hamed, Sam Lismont, LucΓ­a ChΓ‘vez-GutiΓ©rrez, and Rouslan G. Efremov. Apo and aΞ²46-bound Ξ³-secretase structures provide insights into amyloid-Ξ² processing by the aph-1b isoform. Nature Communications, May 2024. URL: https://doi.org/10.1038/s41467-024-48776-2, doi:10.1038/s41467-024-48776-2. This article has 13 citations and is from a highest quality peer-reviewed journal.

  4. (malvankar2026theΞ³secretasecomplex pages 1-4): Shweta R. Malvankar and Michael Scott Wolfe. The Ξ³-secretase complex: from discovery to therapeutic target. RSC Chemical Biology, Jan 2026. URL: https://doi.org/10.1039/d6cb00022c, doi:10.1039/d6cb00022c. This article has 0 citations and is from a peer-reviewed journal.

  5. (strooper2024newprecisionmedicine pages 3-4): Bart de Strooper and Eric H. Karran. New precision medicine avenues to the prevention of alzheimer’s disease from insights into the structure and function of Ξ³-secretases. The EMBO Journal, 43(6):887-903, Feb 2024. URL: https://doi.org/10.1038/s44318-024-00057-w, doi:10.1038/s44318-024-00057-w. This article has 40 citations.

  6. (malvankar2026theΞ³secretasecomplex pages 6-9): Shweta R. Malvankar and Michael Scott Wolfe. The Ξ³-secretase complex: from discovery to therapeutic target. RSC Chemical Biology, Jan 2026. URL: https://doi.org/10.1039/d6cb00022c, doi:10.1039/d6cb00022c. This article has 0 citations and is from a peer-reviewed journal.

  7. (odorcic2024apoandaΞ²46bound pages 4-5): Ivica OdorčiΔ‡, Mohamed Belal Hamed, Sam Lismont, LucΓ­a ChΓ‘vez-GutiΓ©rrez, and Rouslan G. Efremov. Apo and aΞ²46-bound Ξ³-secretase structures provide insights into amyloid-Ξ² processing by the aph-1b isoform. Nature Communications, May 2024. URL: https://doi.org/10.1038/s41467-024-48776-2, doi:10.1038/s41467-024-48776-2. This article has 13 citations and is from a highest quality peer-reviewed journal.

  8. (odorcic2024apoandaΞ²46bound pages 2-4): Ivica OdorčiΔ‡, Mohamed Belal Hamed, Sam Lismont, LucΓ­a ChΓ‘vez-GutiΓ©rrez, and Rouslan G. Efremov. Apo and aΞ²46-bound Ξ³-secretase structures provide insights into amyloid-Ξ² processing by the aph-1b isoform. Nature Communications, May 2024. URL: https://doi.org/10.1038/s41467-024-48776-2, doi:10.1038/s41467-024-48776-2. This article has 13 citations and is from a highest quality peer-reviewed journal.

  9. (strooper2024newprecisionmedicine pages 5-6): Bart de Strooper and Eric H. Karran. New precision medicine avenues to the prevention of alzheimer’s disease from insights into the structure and function of Ξ³-secretases. The EMBO Journal, 43(6):887-903, Feb 2024. URL: https://doi.org/10.1038/s44318-024-00057-w, doi:10.1038/s44318-024-00057-w. This article has 40 citations.

  10. (odorcic2024apoandaΞ²46bound pages 5-7): Ivica OdorčiΔ‡, Mohamed Belal Hamed, Sam Lismont, LucΓ­a ChΓ‘vez-GutiΓ©rrez, and Rouslan G. Efremov. Apo and aΞ²46-bound Ξ³-secretase structures provide insights into amyloid-Ξ² processing by the aph-1b isoform. Nature Communications, May 2024. URL: https://doi.org/10.1038/s41467-024-48776-2, doi:10.1038/s41467-024-48776-2. This article has 13 citations and is from a highest quality peer-reviewed journal.

  11. (strooper2024newprecisionmedicine pages 6-7): Bart de Strooper and Eric H. Karran. New precision medicine avenues to the prevention of alzheimer’s disease from insights into the structure and function of Ξ³-secretases. The EMBO Journal, 43(6):887-903, Feb 2024. URL: https://doi.org/10.1038/s44318-024-00057-w, doi:10.1038/s44318-024-00057-w. This article has 40 citations.

  12. (hou2023theΞ³secretasesubstrate pages 1-4): Pengfei Hou, Magdalena Zielonka, Lutgarde Serneels, Anna Martinez-Muriana, Nicola Fattorelli, Leen Wolfs, Suresh Poovathingal, Dries T'Syen, Sriram Balusu, Tom Theys, Mark Fiers, Renzo Mancuso, Andrew J.M. Howden, and Bart De Strooper. The Ξ³-secretase substrate proteome and its role in cell signaling regulation. Molecular cell, 83 22:4106-4122.e10, Nov 2023. URL: https://doi.org/10.1016/j.molcel.2023.10.029, doi:10.1016/j.molcel.2023.10.029. This article has 27 citations and is from a highest quality peer-reviewed journal.

  13. (malvankar2026theΞ³secretasecomplex pages 11-15): Shweta R. Malvankar and Michael Scott Wolfe. The Ξ³-secretase complex: from discovery to therapeutic target. RSC Chemical Biology, Jan 2026. URL: https://doi.org/10.1039/d6cb00022c, doi:10.1039/d6cb00022c. This article has 0 citations and is from a peer-reviewed journal.

  14. (hou2023theΞ³secretasesubstrate pages 4-6): Pengfei Hou, Magdalena Zielonka, Lutgarde Serneels, Anna Martinez-Muriana, Nicola Fattorelli, Leen Wolfs, Suresh Poovathingal, Dries T'Syen, Sriram Balusu, Tom Theys, Mark Fiers, Renzo Mancuso, Andrew J.M. Howden, and Bart De Strooper. The Ξ³-secretase substrate proteome and its role in cell signaling regulation. Molecular cell, 83 22:4106-4122.e10, Nov 2023. URL: https://doi.org/10.1016/j.molcel.2023.10.029, doi:10.1016/j.molcel.2023.10.029. This article has 27 citations and is from a highest quality peer-reviewed journal.

  15. (strooper2024newprecisionmedicine pages 4-5): Bart de Strooper and Eric H. Karran. New precision medicine avenues to the prevention of alzheimer’s disease from insights into the structure and function of Ξ³-secretases. The EMBO Journal, 43(6):887-903, Feb 2024. URL: https://doi.org/10.1038/s44318-024-00057-w, doi:10.1038/s44318-024-00057-w. This article has 40 citations.

  16. (vilyaninov2024Ξ³secretaseinthe pages 3-6): Vladimir N. Vilyaninov, Vladimir I. Vashchenko, and Petr D. Shabanov. Ξ“-secretase in the pathogenesis of alzheimer’s disease and therapeutic potential of its modulators. Psychopharmacology & biological narcology, 15:211-236, Oct 2024. URL: https://doi.org/10.17816/phbn635851, doi:10.17816/phbn635851. This article has 0 citations.

  17. (malvankar2026theΞ³secretasecomplex pages 15-17): Shweta R. Malvankar and Michael Scott Wolfe. The Ξ³-secretase complex: from discovery to therapeutic target. RSC Chemical Biology, Jan 2026. URL: https://doi.org/10.1039/d6cb00022c, doi:10.1039/d6cb00022c. This article has 0 citations and is from a peer-reviewed journal.

  18. (strooper2024newprecisionmedicine pages 2-3): Bart de Strooper and Eric H. Karran. New precision medicine avenues to the prevention of alzheimer’s disease from insights into the structure and function of Ξ³-secretases. The EMBO Journal, 43(6):887-903, Feb 2024. URL: https://doi.org/10.1038/s44318-024-00057-w, doi:10.1038/s44318-024-00057-w. This article has 40 citations.

Artifacts

Citations

  1. strooper2024newprecisionmedicine pages 3-4
  2. strooper2024newprecisionmedicine pages 4-5
  3. strooper2024newprecisionmedicine pages 6-7
  4. strooper2024newprecisionmedicine pages 2-3
  5. strooper2024newprecisionmedicine pages 1-2
  6. ning2025themanipulatorbehind pages 2-4
  7. strooper2024newprecisionmedicine pages 5-6
  8. https://doi.org/10.1038/s44318-024-00057-w,
  9. https://doi.org/10.3389/fnagi.2025.1637671,
  10. https://doi.org/10.1038/s41467-024-48776-2,
  11. https://doi.org/10.1039/d6cb00022c,
  12. https://doi.org/10.1016/j.molcel.2023.10.029,
  13. https://doi.org/10.17816/phbn635851,

πŸ“š Additional Documentation

Notes

(APH1A-notes.md)

APH1A curation notes

2026-06-19

  • Deep-research attempt with just deep-research-falcon human APH1A --fallback perplexity-lite timed out after 180 seconds with no generated research artifact, so this manual review uses cached UniProt, GOA, and publication evidence.
  • APH1A encodes a multipass non-catalytic gamma-secretase subunit. UniProt summarizes APH1A as a component of the endoprotease complex that cleaves integral membrane substrates including Notch receptors and APP, and says APH1A is required for normal complex assembly.
  • Direct APH1A evidence supports complex membership and substrate processing: the Lee et al. abstract states that mammalian APH-1 "physically associates with nicastrin and the heterodimers of the presenilin" and that APH-1 knockdown reduces amyloid-beta peptides plus APP and Notch intracellular domains [PMID:12297508 "physically associates with nicastrin and the heterodimers of the presenilin"; PMID:12297508 "reduction of gamma-secretase products (amyloid-beta peptides and the intracellular domains of APP and Notch)"].
  • APH1A should be curated as a non-catalytic adaptor/assembly/activator subunit, not as an independent peptidase. The complex contains presenilin, Pen-2, Aph-1, and nicastrin PMID:25043039, while presenilin is the catalytic aspartyl protease subunit in the complex.
  • APP and Notch processing are core outputs. The APH1A-containing complex cleaves APP-C100 in vitro PMID:25043039 and older RNAi/overexpression work describes APH1/PEN2/nicastrin as essential or limiting for gamma-secretase activity PMID:12763021.
  • The steady-state localization emphasis for APH1A is ER and cis-Golgi, with membrane and endomembrane annotations biologically consistent. Plasma-membrane Reactome annotations probably reflect substrate event locations rather than the strongest APH1A-specific localization evidence, so I treated them as retained but non-core.
  • Generic protein binding annotations capture real interactions but are not informative GO molecular-function statements for APH1A. I marked those as over-annotated rather than removing them, because several are experimental interaction datasets and complex membership is real.

2026-06-20 second-pass audit

The second-pass audit added manual reference_review metadata for the main APH1A/gamma-secretase papers documenting APH-1 association with presenilin/nicastrin, APP and Notch proteolysis, purified human gamma-secretase composition, and APH1 isoform effects on substrate cleavage. No annotation action changes were needed: APH1A remains curated as a non-catalytic scaffold/adaptor subunit required for gamma-secretase assembly and complex-level intramembrane protease activity, not as an independent protease.

Falcon deep research integration (2026-06-21)

A Falcon (Edison) deep-research report is now present in APH1A-deep-research-falcon.md; it corroborates the existing review well, reaffirming APH1A as a non-catalytic, multipass-membrane scaffold/stabilizer subunit of the four-component gamma-secretase complex (presenilin/PSEN, nicastrin/NCSTN, PEN-2/PSENEN) acting in APP processing/amyloid-beta generation and Notch processing, with no annotation actions overturned. The Falcon-sourced citations below are not yet independently verified against full text.

New or refined points beyond the existing notes/review:
- Membrane topology refined to seven transmembrane domains with N-terminus extracellular/luminal and C-terminus cytosolic, consistent with a structural core role [Malvankar & Wolfe, RSC Chem. Biol. 2026, doi:10.1039/d6cb00022c; OdorčiΔ‡ et al., Nat. Commun. 2024, doi:10.1038/s41467-024-48776-2].
- Cryo-EM architecture: APH-1 forms a major (~2,000 Γ…Β²) membrane-embedded interface with presenilin (APH-1 TM2-TM4 contacting PSEN1 TM1 and TM8-TM9; PSEN1 C-terminus inserts into the APH-1 helical bundle), giving a structural basis for the "presenilin-stabilization factor" alias [OdorčiΔ‡ et al., Nat. Commun. 2024, doi:10.1038/s41467-024-48776-2].
- Ordered stepwise assembly: NCSTN+APH1A form an early ER subcomplex, which then recruits full-length presenilin, after which PEN-2/PSENEN binds (via PSEN TMD4) to trigger presenilin autoproteolysis (NTF/CTF); complex matures in the Golgi with nicastrin glycosylation [Malvankar & Wolfe 2026, doi:10.1039/d6cb00022c; Ning et al., Front. Aging Neurosci. 2025, doi:10.3389/fnagi.2025.1637671].
- APH1A vs APH1B isoform distinction: APH1A(+PSEN1) complexes are associated with greater substrate processivity and relatively shorter Abeta products, whereas PSEN2/APH1B complexes favor longer aggregation-prone Abeta (Abeta42/43); APH-1 isoform divergence clusters in ~3 non-conserved regions including the TM3-TM4 loop implicated in substrate-induced allosteric coupling [OdorčiΔ‡ et al. 2024, doi:10.1038/s41467-024-48776-2; de Strooper & Karran, EMBO J. 2024, doi:10.1038/s44318-024-00057-w]. (NB: the OdorčiΔ‡ structure is of the APH-1B complex; APH1A is the comparison reference, so APH1A-specific claims are inferential.)
- Genetic essentiality: Aph1a knockout causes lethal Notch phenotypes in mouse embryogenesis vs. only mild deficits for Aph1b, marking APH1A as the predominant paralog for developmental Notch signaling [de Strooper & Karran 2024, doi:10.1038/s44318-024-00057-w].
- Broader substrate proteome: gamma-secretase processes >145-150 type I membrane substrates; the 2023 G-SECSI screen found 85 microglial substrates (59 novel), positioning APH1A within a wide regulated-intramembrane-proteolysis network [Hou et al., Mol. Cell 2023, doi:10.1016/j.molcel.2023.10.029].
- Pharmacology context: nirogacestat (first gamma-secretase inhibitor, FDA-approved 2023 for desmoid tumors) and complex-selective modulator concepts; some compounds discriminate APH1A- vs APH1B-containing complexes [de Strooper & Karran 2024, doi:10.1038/s44318-024-00057-w].

Discrepancies / annotations to revisit:
- No contradictions with the existing review or its annotation actions; the report reinforces every retained core function.
- The new seven-TM topology and cryo-EM interface data strengthen (do not change) the existing GO:0030674 protein-macromolecule adaptor activity and GO:0061133 endopeptidase activator activity calls, and the membership call GO:0070765 gamma-secretase complex.
- The report's substrate-proteome breadth (p75NTR, ERBB4, EphB2, etc.) is consistent with the existing Reactome-derived plasma-membrane annotations kept as non-core; nothing here argues for promoting plasma membrane (GO:0005886) to core, since APH1A steady-state localization remains ER/cis-Golgi-dominant.
- Optional consideration only (not required): the report's emphasis on APH1A's role in stepwise gamma-secretase assembly/maturation could motivate adding a protein-complex-assembly process term in proposed_new_terms (exact GO ID to be looked up via OLS, not guessed here); current core_functions already capture the adaptor/assembly intent, so this is left as a possible future refinement pending full-text verification.

πŸ“„ View Raw YAML

 
id: Q96BI3
gene_symbol: APH1A
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: 'APH1A encodes gamma-secretase subunit APH-1A, a multipass membrane protein and
  essential non-catalytic component of the gamma-secretase intramembrane protease complex.
  Together with a presenilin catalytic subunit, nicastrin, and PSENEN/PEN-2, APH1A supports
  complex assembly, stability, and activity toward membrane substrates including APP and Notch
  receptors. APH1A is enriched in endoplasmic-reticulum and cis-Golgi membranes and participates
  in regulated intramembrane proteolysis within membrane and endomembrane compartments.'
alternative_products:
- name: 1 (L, Aph-alpha1)
  id: Q96BI3-1
- name: 2 (S, Aph-alpha2)
  id: Q96BI3-2
  sequence_note: VSP_008355, VSP_008356
- name: '3'
  id: Q96BI3-3
  sequence_note: VSP_045424
existing_annotations:
- term:
    id: GO:0070765
    label: gamma-secretase complex
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: part_of
  review:
    summary: APH1A is an established non-catalytic subunit of the gamma-secretase 
      complex with presenilin, nicastrin, and PSENEN/PEN-2.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0034205
    label: amyloid-beta formation
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: APH1A-containing gamma-secretase participates in APP processing that 
      generates amyloid-beta-related products.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0016485
    label: protein processing
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: This captures the core regulated intramembrane processing activity of the 
      APH1A-containing gamma-secretase complex.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0030674
    label: protein-macromolecule adaptor activity
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: enables
  review:
    summary: APH1A acts as a non-catalytic assembly/adaptor subunit that helps stabilize
      and organize active gamma-secretase complexes.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0007220
    label: Notch receptor processing
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: APH1A supports gamma-secretase-dependent Notch receptor processing and 
      release of Notch intracellular domains.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0007219
    label: Notch signaling pathway
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: Notch signaling is a downstream pathway output of gamma-secretase-mediated 
      Notch receptor processing.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0005789
    label: endoplasmic reticulum membrane
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: This membrane or endomembrane location is consistent with APH1A as a 
      multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
    action: ACCEPT
    reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, 
      Golgi, endosomal, and general membrane localizations are consistent with the 
      curated biology.
- term:
    id: GO:0006508
    label: proteolysis
  evidence_type: IEA
  original_reference_id: GO_REF:0000117
  qualifier: involved_in
  review:
    summary: Generic proteolysis is too broad for APH1A; the supported process is 
      gamma-secretase-dependent intramembrane processing of membrane substrates.
    action: MODIFY
    proposed_replacement_terms:
    - id: GO:0031293
      label: membrane protein intracellular domain proteolysis
    - id: GO:0016485
      label: protein processing
    reason: Replace the broad proteolysis term with the more specific regulated 
      intramembrane-processing terms supported for gamma-secretase.
- term:
    id: GO:0016020
    label: membrane
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: located_in
  review:
    summary: This membrane or endomembrane location is consistent with APH1A as a 
      multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
    action: ACCEPT
    reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, 
      Golgi, endosomal, and general membrane localizations are consistent with the 
      curated biology.
- term:
    id: GO:0016485
    label: protein processing
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: involved_in
  review:
    summary: This captures the core regulated intramembrane processing activity of the 
      APH1A-containing gamma-secretase complex.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0032580
    label: Golgi cisterna membrane
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: This membrane or endomembrane location is consistent with APH1A as a 
      multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
    action: ACCEPT
    reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, 
      Golgi, endosomal, and general membrane localizations are consistent with the 
      curated biology.
- term:
    id: GO:0070765
    label: gamma-secretase complex
  evidence_type: IEA
  original_reference_id: GO_REF:0000117
  qualifier: part_of
  review:
    summary: APH1A is an established non-catalytic subunit of the gamma-secretase 
      complex with presenilin, nicastrin, and PSENEN/PEN-2.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:12297508
  qualifier: enables
  review:
    summary: The interaction evidence is compatible with APH1A complex membership, but 
      generic protein binding is not an informative molecular function for this gene.
    action: MARK_AS_OVER_ANNOTATED
    reason: Prefer complex membership and adaptor/activator terms over a broad 
      protein-binding annotation.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:18201567
  qualifier: enables
  review:
    summary: The interaction evidence is compatible with APH1A complex membership, but 
      generic protein binding is not an informative molecular function for this gene.
    action: MARK_AS_OVER_ANNOTATED
    reason: Prefer complex membership and adaptor/activator terms over a broad 
      protein-binding annotation.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:19376115
  qualifier: enables
  review:
    summary: The interaction evidence is compatible with APH1A complex membership, but 
      generic protein binding is not an informative molecular function for this gene.
    action: MARK_AS_OVER_ANNOTATED
    reason: Prefer complex membership and adaptor/activator terms over a broad 
      protein-binding annotation.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:23864651
  qualifier: enables
  review:
    summary: The interaction evidence is compatible with APH1A complex membership, but 
      generic protein binding is not an informative molecular function for this gene.
    action: MARK_AS_OVER_ANNOTATED
    reason: Prefer complex membership and adaptor/activator terms over a broad 
      protein-binding annotation.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:25394380
  qualifier: enables
  review:
    summary: The interaction evidence is compatible with APH1A complex membership, but 
      generic protein binding is not an informative molecular function for this gene.
    action: MARK_AS_OVER_ANNOTATED
    reason: Prefer complex membership and adaptor/activator terms over a broad 
      protein-binding annotation.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:26280335
  qualifier: enables
  review:
    summary: The interaction evidence is compatible with APH1A complex membership, but 
      generic protein binding is not an informative molecular function for this gene.
    action: MARK_AS_OVER_ANNOTATED
    reason: Prefer complex membership and adaptor/activator terms over a broad 
      protein-binding annotation.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:30559186
  qualifier: enables
  review:
    summary: The interaction evidence is compatible with APH1A complex membership, but 
      generic protein binding is not an informative molecular function for this gene.
    action: MARK_AS_OVER_ANNOTATED
    reason: Prefer complex membership and adaptor/activator terms over a broad 
      protein-binding annotation.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32296183
  qualifier: enables
  review:
    summary: The interaction evidence is compatible with APH1A complex membership, but 
      generic protein binding is not an informative molecular function for this gene.
    action: MARK_AS_OVER_ANNOTATED
    reason: Prefer complex membership and adaptor/activator terms over a broad 
      protein-binding annotation.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32814053
  qualifier: enables
  review:
    summary: The interaction evidence is compatible with APH1A complex membership, but 
      generic protein binding is not an informative molecular function for this gene.
    action: MARK_AS_OVER_ANNOTATED
    reason: Prefer complex membership and adaptor/activator terms over a broad 
      protein-binding annotation.
- term:
    id: GO:0019899
    label: enzyme binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: enables
  review:
    summary: Broad enzyme binding is plausible for an APH1A gamma-secretase subunit but 
      is less informative than adaptor/activator and complex-membership annotations.
    action: KEEP_AS_NON_CORE
    reason: Retain as non-core because it may reflect real association with the 
      presenilin protease but does not define APH1A primary molecular role.
- term:
    id: GO:0061133
    label: endopeptidase activator activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: enables
  review:
    summary: APH1A is required for normal gamma-secretase assembly and activity, 
      supporting an endopeptidase activator role at the complex level.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0005789
    label: endoplasmic reticulum membrane
  evidence_type: EXP
  original_reference_id: PMID:12522139
  qualifier: located_in
  review:
    summary: This membrane or endomembrane location is consistent with APH1A as a 
      multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
    action: ACCEPT
    reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, 
      Golgi, endosomal, and general membrane localizations are consistent with the 
      curated biology.
- term:
    id: GO:0005789
    label: endoplasmic reticulum membrane
  evidence_type: NAS
  original_reference_id: PMID:15274632
  qualifier: located_in
  review:
    summary: This membrane or endomembrane location is consistent with APH1A as a 
      multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
    action: ACCEPT
    reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, 
      Golgi, endosomal, and general membrane localizations are consistent with the 
      curated biology.
- term:
    id: GO:0005886
    label: plasma membrane
  evidence_type: IDA
  original_reference_id: PMID:15274632
  qualifier: located_in
  review:
    summary: Plasma-membrane annotations are plausible for gamma-secretase substrate 
      events, but APH1A-specific steady-state localization is strongest for ER and 
      cis-Golgi membranes.
    action: KEEP_AS_NON_CORE
    reason: Retain as non-core because the site is biologically plausible for substrate 
      processing without being the clearest APH1A-defining location.
- term:
    id: GO:0007220
    label: Notch receptor processing
  evidence_type: NAS
  original_reference_id: PMID:10206645
  qualifier: involved_in
  review:
    summary: APH1A supports gamma-secretase-dependent Notch receptor processing and 
      release of Notch intracellular domains.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0031293
    label: membrane protein intracellular domain proteolysis
  evidence_type: IDA
  original_reference_id: PMID:15274632
  qualifier: involved_in
  review:
    summary: This captures the core regulated intramembrane processing activity of the 
      APH1A-containing gamma-secretase complex.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0042987
    label: amyloid precursor protein catabolic process
  evidence_type: IDA
  original_reference_id: PMID:15274632
  qualifier: involved_in
  review:
    summary: APH1A-containing gamma-secretase participates in APP processing that 
      generates amyloid-beta-related products.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0070765
    label: gamma-secretase complex
  evidence_type: IPI
  original_reference_id: PMID:26280335
  qualifier: part_of
  review:
    summary: APH1A is an established non-catalytic subunit of the gamma-secretase 
      complex with presenilin, nicastrin, and PSENEN/PEN-2.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0000139
    label: Golgi membrane
  evidence_type: NAS
  original_reference_id: PMID:15274632
  qualifier: located_in
  review:
    summary: This membrane or endomembrane location is consistent with APH1A as a 
      multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
    action: ACCEPT
    reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, 
      Golgi, endosomal, and general membrane localizations are consistent with the 
      curated biology.
- term:
    id: GO:0007220
    label: Notch receptor processing
  evidence_type: IMP
  original_reference_id: PMID:12297508
  qualifier: involved_in
  review:
    summary: APH1A supports gamma-secretase-dependent Notch receptor processing and 
      release of Notch intracellular domains.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0007220
    label: Notch receptor processing
  evidence_type: IDA
  original_reference_id: PMID:27608597
  qualifier: involved_in
  review:
    summary: APH1A supports gamma-secretase-dependent Notch receptor processing and 
      release of Notch intracellular domains.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0016485
    label: protein processing
  evidence_type: IMP
  original_reference_id: PMID:12297508
  qualifier: involved_in
  review:
    summary: This captures the core regulated intramembrane processing activity of the 
      APH1A-containing gamma-secretase complex.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0016485
    label: protein processing
  evidence_type: IGI
  original_reference_id: PMID:12763021
  qualifier: involved_in
  review:
    summary: This captures the core regulated intramembrane processing activity of the 
      APH1A-containing gamma-secretase complex.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0016485
    label: protein processing
  evidence_type: IDA
  original_reference_id: PMID:27608597
  qualifier: involved_in
  review:
    summary: This captures the core regulated intramembrane processing activity of the 
      APH1A-containing gamma-secretase complex.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0030674
    label: protein-macromolecule adaptor activity
  evidence_type: IMP
  original_reference_id: PMID:12297508
  qualifier: enables
  review:
    summary: APH1A acts as a non-catalytic assembly/adaptor subunit that helps stabilize
      and organize active gamma-secretase complexes.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0034205
    label: amyloid-beta formation
  evidence_type: IMP
  original_reference_id: PMID:12297508
  qualifier: involved_in
  review:
    summary: APH1A-containing gamma-secretase participates in APP processing that 
      generates amyloid-beta-related products.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0034205
    label: amyloid-beta formation
  evidence_type: IGI
  original_reference_id: PMID:12763021
  qualifier: involved_in
  review:
    summary: APH1A-containing gamma-secretase participates in APP processing that 
      generates amyloid-beta-related products.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0034205
    label: amyloid-beta formation
  evidence_type: IDA
  original_reference_id: PMID:27608597
  qualifier: involved_in
  review:
    summary: APH1A-containing gamma-secretase participates in APP processing that 
      generates amyloid-beta-related products.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0042987
    label: amyloid precursor protein catabolic process
  evidence_type: IGI
  original_reference_id: PMID:12763021
  qualifier: involved_in
  review:
    summary: APH1A-containing gamma-secretase participates in APP processing that 
      generates amyloid-beta-related products.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0042987
    label: amyloid precursor protein catabolic process
  evidence_type: IDA
  original_reference_id: PMID:27608597
  qualifier: involved_in
  review:
    summary: APH1A-containing gamma-secretase participates in APP processing that 
      generates amyloid-beta-related products.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0061133
    label: endopeptidase activator activity
  evidence_type: IMP
  original_reference_id: PMID:12297508
  qualifier: enables
  review:
    summary: APH1A is required for normal gamma-secretase assembly and activity, 
      supporting an endopeptidase activator role at the complex level.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0061133
    label: endopeptidase activator activity
  evidence_type: IGI
  original_reference_id: PMID:12763021
  qualifier: enables
  review:
    summary: APH1A is required for normal gamma-secretase assembly and activity, 
      supporting an endopeptidase activator role at the complex level.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0070765
    label: gamma-secretase complex
  evidence_type: IDA
  original_reference_id: PMID:12297508
  qualifier: part_of
  review:
    summary: APH1A is an established non-catalytic subunit of the gamma-secretase 
      complex with presenilin, nicastrin, and PSENEN/PEN-2.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0010008
    label: endosome membrane
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-9010096
  qualifier: located_in
  review:
    summary: This membrane or endomembrane location is consistent with APH1A as a 
      multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
    action: ACCEPT
    reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, 
      Golgi, endosomal, and general membrane localizations are consistent with the 
      curated biology.
- term:
    id: GO:0016020
    label: membrane
  evidence_type: IDA
  original_reference_id: PMID:25043039
  qualifier: located_in
  review:
    summary: This membrane or endomembrane location is consistent with APH1A as a 
      multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
    action: ACCEPT
    reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, 
      Golgi, endosomal, and general membrane localizations are consistent with the 
      curated biology.
- term:
    id: GO:0016020
    label: membrane
  evidence_type: IDA
  original_reference_id: PMID:26280335
  qualifier: located_in
  review:
    summary: This membrane or endomembrane location is consistent with APH1A as a 
      multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
    action: ACCEPT
    reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, 
      Golgi, endosomal, and general membrane localizations are consistent with the 
      curated biology.
- term:
    id: GO:0034205
    label: amyloid-beta formation
  evidence_type: IMP
  original_reference_id: PMID:25043039
  qualifier: involved_in
  review:
    summary: APH1A-containing gamma-secretase participates in APP processing that 
      generates amyloid-beta-related products.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0034205
    label: amyloid-beta formation
  evidence_type: IMP
  original_reference_id: PMID:26280335
  qualifier: involved_in
  review:
    summary: APH1A-containing gamma-secretase participates in APP processing that 
      generates amyloid-beta-related products.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0042982
    label: amyloid precursor protein metabolic process
  evidence_type: IDA
  original_reference_id: PMID:25043039
  qualifier: involved_in
  review:
    summary: APH1A-containing gamma-secretase participates in APP processing that 
      generates amyloid-beta-related products.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0042982
    label: amyloid precursor protein metabolic process
  evidence_type: IDA
  original_reference_id: PMID:26280335
  qualifier: involved_in
  review:
    summary: APH1A-containing gamma-secretase participates in APP processing that 
      generates amyloid-beta-related products.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0070765
    label: gamma-secretase complex
  evidence_type: IDA
  original_reference_id: PMID:25043039
  qualifier: part_of
  review:
    summary: APH1A is an established non-catalytic subunit of the gamma-secretase 
      complex with presenilin, nicastrin, and PSENEN/PEN-2.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0070765
    label: gamma-secretase complex
  evidence_type: IDA
  original_reference_id: PMID:26280335
  qualifier: part_of
  review:
    summary: APH1A is an established non-catalytic subunit of the gamma-secretase 
      complex with presenilin, nicastrin, and PSENEN/PEN-2.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0016020
    label: membrane
  evidence_type: HDA
  original_reference_id: PMID:19946888
  qualifier: located_in
  review:
    summary: This membrane or endomembrane location is consistent with APH1A as a 
      multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
    action: ACCEPT
    reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, 
      Golgi, endosomal, and general membrane localizations are consistent with the 
      curated biology.
- term:
    id: GO:0005886
    label: plasma membrane
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-1251997
  qualifier: located_in
  review:
    summary: Plasma-membrane annotations are plausible for gamma-secretase substrate 
      events, but APH1A-specific steady-state localization is strongest for ER and 
      cis-Golgi membranes.
    action: KEEP_AS_NON_CORE
    reason: Retain as non-core because the site is biologically plausible for substrate 
      processing without being the clearest APH1A-defining location.
- term:
    id: GO:0005886
    label: plasma membrane
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-193682
  qualifier: located_in
  review:
    summary: Plasma-membrane annotations are plausible for gamma-secretase substrate 
      events, but APH1A-specific steady-state localization is strongest for ER and 
      cis-Golgi membranes.
    action: KEEP_AS_NON_CORE
    reason: Retain as non-core because the site is biologically plausible for substrate 
      processing without being the clearest APH1A-defining location.
- term:
    id: GO:0005886
    label: plasma membrane
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-205112
  qualifier: located_in
  review:
    summary: Plasma-membrane annotations are plausible for gamma-secretase substrate 
      events, but APH1A-specific steady-state localization is strongest for ER and 
      cis-Golgi membranes.
    action: KEEP_AS_NON_CORE
    reason: Retain as non-core because the site is biologically plausible for substrate 
      processing without being the clearest APH1A-defining location.
- term:
    id: GO:0005886
    label: plasma membrane
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-2220988
  qualifier: located_in
  review:
    summary: Plasma-membrane annotations are plausible for gamma-secretase substrate 
      events, but APH1A-specific steady-state localization is strongest for ER and 
      cis-Golgi membranes.
    action: KEEP_AS_NON_CORE
    reason: Retain as non-core because the site is biologically plausible for substrate 
      processing without being the clearest APH1A-defining location.
- term:
    id: GO:0005886
    label: plasma membrane
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-3928656
  qualifier: located_in
  review:
    summary: Plasma-membrane annotations are plausible for gamma-secretase substrate 
      events, but APH1A-specific steady-state localization is strongest for ER and 
      cis-Golgi membranes.
    action: KEEP_AS_NON_CORE
    reason: Retain as non-core because the site is biologically plausible for substrate 
      processing without being the clearest APH1A-defining location.
- term:
    id: GO:0005886
    label: plasma membrane
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-9013361
  qualifier: located_in
  review:
    summary: Plasma-membrane annotations are plausible for gamma-secretase substrate 
      events, but APH1A-specific steady-state localization is strongest for ER and 
      cis-Golgi membranes.
    action: KEEP_AS_NON_CORE
    reason: Retain as non-core because the site is biologically plausible for substrate 
      processing without being the clearest APH1A-defining location.
- term:
    id: GO:0005886
    label: plasma membrane
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-9017817
  qualifier: located_in
  review:
    summary: Plasma-membrane annotations are plausible for gamma-secretase substrate 
      events, but APH1A-specific steady-state localization is strongest for ER and 
      cis-Golgi membranes.
    action: KEEP_AS_NON_CORE
    reason: Retain as non-core because the site is biologically plausible for substrate 
      processing without being the clearest APH1A-defining location.
- term:
    id: GO:0005886
    label: plasma membrane
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-9839376
  qualifier: located_in
  review:
    summary: Plasma-membrane annotations are plausible for gamma-secretase substrate 
      events, but APH1A-specific steady-state localization is strongest for ER and 
      cis-Golgi membranes.
    action: KEEP_AS_NON_CORE
    reason: Retain as non-core because the site is biologically plausible for substrate 
      processing without being the clearest APH1A-defining location.
- term:
    id: GO:0005886
    label: plasma membrane
  evidence_type: TAS
  original_reference_id: Reactome:R-NUL-2197556
  qualifier: located_in
  review:
    summary: Plasma-membrane annotations are plausible for gamma-secretase substrate 
      events, but APH1A-specific steady-state localization is strongest for ER and 
      cis-Golgi membranes.
    action: KEEP_AS_NON_CORE
    reason: Retain as non-core because the site is biologically plausible for substrate 
      processing without being the clearest APH1A-defining location.
- term:
    id: GO:0005886
    label: plasma membrane
  evidence_type: TAS
  original_reference_id: Reactome:R-NUL-9604300
  qualifier: located_in
  review:
    summary: Plasma-membrane annotations are plausible for gamma-secretase substrate 
      events, but APH1A-specific steady-state localization is strongest for ER and 
      cis-Golgi membranes.
    action: KEEP_AS_NON_CORE
    reason: Retain as non-core because the site is biologically plausible for substrate 
      processing without being the clearest APH1A-defining location.
- term:
    id: GO:0031293
    label: membrane protein intracellular domain proteolysis
  evidence_type: IMP
  original_reference_id: PMID:12297508
  qualifier: involved_in
  review:
    summary: This captures the core regulated intramembrane processing activity of the 
      APH1A-containing gamma-secretase complex.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0042987
    label: amyloid precursor protein catabolic process
  evidence_type: IMP
  original_reference_id: PMID:12297508
  qualifier: involved_in
  review:
    summary: APH1A-containing gamma-secretase participates in APP processing that 
      generates amyloid-beta-related products.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0005783
    label: endoplasmic reticulum
  evidence_type: IDA
  original_reference_id: PMID:15274632
  qualifier: located_in
  review:
    summary: This membrane or endomembrane location is consistent with APH1A as a 
      multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
    action: ACCEPT
    reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, 
      Golgi, endosomal, and general membrane localizations are consistent with the 
      curated biology.
- term:
    id: GO:0005794
    label: Golgi apparatus
  evidence_type: IDA
  original_reference_id: PMID:15274632
  qualifier: located_in
  review:
    summary: This membrane or endomembrane location is consistent with APH1A as a 
      multipass gamma-secretase subunit, especially its ER/cis-Golgi localization.
    action: ACCEPT
    reason: APH1A is a multipass membrane protein in the gamma-secretase complex; ER, 
      Golgi, endosomal, and general membrane localizations are consistent with the 
      curated biology.
- term:
    id: GO:0006509
    label: membrane protein ectodomain proteolysis
  evidence_type: IDA
  original_reference_id: PMID:15274632
  qualifier: involved_in
  review:
    summary: Gamma-secretase acts after ectodomain shedding and performs intramembrane 
      cleavage; ectodomain proteolysis is not the best APH1A process label.
    action: MODIFY
    proposed_replacement_terms:
    - id: GO:0031293
      label: membrane protein intracellular domain proteolysis
    - id: GO:0016485
      label: protein processing
    reason: Use an intramembrane substrate-processing term rather than ectodomain 
      proteolysis for the APH1A-containing gamma-secretase complex.
- term:
    id: GO:0007220
    label: Notch receptor processing
  evidence_type: TAS
  original_reference_id: PMID:15274632
  qualifier: involved_in
  review:
    summary: APH1A supports gamma-secretase-dependent Notch receptor processing and 
      release of Notch intracellular domains.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0016485
    label: protein processing
  evidence_type: IDA
  original_reference_id: PMID:15274632
  qualifier: involved_in
  review:
    summary: This captures the core regulated intramembrane processing activity of the 
      APH1A-containing gamma-secretase complex.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
- term:
    id: GO:0042987
    label: amyloid precursor protein catabolic process
  evidence_type: TAS
  original_reference_id: PMID:15274632
  qualifier: involved_in
  review:
    summary: APH1A-containing gamma-secretase participates in APP processing that 
      generates amyloid-beta-related products.
    action: ACCEPT
    reason: The term aligns with APH1A function as a non-catalytic gamma-secretase 
      subunit that supports complex assembly/activity and APP/Notch intramembrane 
      processing.
references:
- id: GO_REF:0000002
  title: Gene Ontology annotation through association of InterPro records with GO terms
  findings: []
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: GO_REF:0000044
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location 
    vocabulary mapping, accompanied by conservative changes to GO terms applied by 
    UniProt
  findings: []
- id: GO_REF:0000107
  title: Automatic transfer of experimentally verified manual GO annotation data to 
    orthologs using Ensembl Compara
  findings: []
- id: GO_REF:0000117
  title: Electronic Gene Ontology annotations created by ARBA machine learning models
  findings: []
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings: []
- id: PMID:10206645
  title: A presenilin-1-dependent gamma-secretase-like protease mediates release of 
    Notch intracellular domain.
  findings: []
- id: PMID:12297508
  title: Mammalian APH-1 interacts with presenilin and nicastrin and is required for 
    intramembrane proteolysis of amyloid-beta precursor protein and Notch.
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Cached abstract directly supports APH-1 physical association
      with presenilin/nicastrin and requirement for APP and Notch 
      intramembrane proteolysis.
- id: PMID:12522139
  title: PEN-2 and APH-1 coordinately regulate proteolytic processing of presenilin 1.
  findings: []
- id: PMID:12763021
  title: APH1, PEN2, and Nicastrin increase Abeta levels and gamma-secretase activity.
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Cached abstract supports APH1 as a gamma-secretase component
      whose expression can increase Abeta levels and gamma-secretase activity.
- id: PMID:15274632
  title: Purification and characterization of the human gamma-secretase complex.
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Cached abstract identifies APH-1 with presenilin, nicastrin,
      and Pen-2 as components of purified active human gamma-secretase.
- id: PMID:18201567
  title: Cellular localization of Nicastrin affects amyloid beta species production.
  findings: []
- id: PMID:19376115
  title: An alternative spliced mouse presenilin-2 mRNA encodes a novel gamma-secretase 
    inhibitor.
  findings: []
- id: PMID:19946888
  title: Defining the membrane proteome of NK cells.
  findings: []
- id: PMID:23864651
  title: The identification of novel proteins that interact with the GLP-1 receptor and 
    restrain its activity.
  findings: []
- id: PMID:25043039
  title: Three-dimensional structure of human Ξ³-secretase.
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Cached full-text record supports the human gamma-secretase
      structural model containing APH-1 with presenilin, nicastrin, and Pen-2.
- id: PMID:25394380
  title: G206D Mutation of Presenilin-1 Reduces Pen2 Interaction, Increases AΞ²42/AΞ²40 
    Ratio and Elevates ER Ca(2+) Accumulation.
  findings: []
- id: PMID:26280335
  title: An atomic structure of human Ξ³-secretase.
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Cached full-text record supports APH-1 as a scaffold in the
      atomic human gamma-secretase structure.
- id: PMID:27608597
  title: Specific combinations of presenilins and Aph1s affect the substrate specificity
    and activity of Ξ³-secretase.
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Cached abstract directly addresses APH1 isoform combinations
      and their effects on APP and Notch cleavage by gamma-secretase.
- id: PMID:30559186
  title: Bax inhibitor 1 is a Ξ³-secretase-independent presenilin-binding protein.
  findings: []
- id: PMID:32296183
  title: A reference map of the human binary protein interactome.
  findings: []
- id: PMID:32814053
  title: Interactome Mapping Provides a Network of Neurodegenerative Disease Proteins 
    and Uncovers Widespread Protein Aggregation in Affected Brains.
  findings: []
- id: Reactome:R-HSA-1251997
  title: Cleavage of ERBB4m80 by gamma-scretase complex
  findings: []
- id: Reactome:R-HSA-193682
  title: gamma-secretase cleaves the p75NTR transmembrane domain
  findings: []
- id: Reactome:R-HSA-205112
  title: gamma-secretase cleaves p75NTR, releasing NRIF and TRAF6
  findings: []
- id: Reactome:R-HSA-2220988
  title: NEXT1 PEST domain mutants are cleaved to produce NICD1 PEST domain mutants
  findings: []
- id: Reactome:R-HSA-3928656
  title: gamma-secretase cleaves EPHB2
  findings: []
- id: Reactome:R-HSA-9010096
  title: Gamma-secretase cleaves APP(672-770) to APP(672-711) and APP(672-713)
  findings: []
- id: Reactome:R-HSA-9013361
  title: NEXT3 is cleaved to produce NICD3
  findings: []
- id: Reactome:R-HSA-9017817
  title: Gamma-secretase cleaves YBX1:NOTCH3
  findings: []
- id: Reactome:R-HSA-9839376
  title: TGFBR3(784-851) degradation
  findings: []
- id: Reactome:R-NUL-2197556
  title: Gamma-secretase complex cleaves mNEXT2
  findings: []
- id: Reactome:R-NUL-9604300
  title: Gamma-secretase cleaves Notch4
  findings: []
- id: file:human/APH1A/APH1A-deep-research-falcon.md
  title: Falcon deep research report for APH1A
  findings:
  - statement: Falcon corroborates the review's core framing of APH1A as a non-catalytic
      scaffold/assembly subunit that allosterically tunes gamma-secretase substrate
      processing rather than catalyzing cleavage itself.
    supporting_text: APH1A also exerts allosteric effects on substrate processing,
      particularly influencing the processivity of sequential intramembrane cleavage.
core_functions:
- molecular_function:
    id: GO:0030674
    label: protein-macromolecule adaptor activity
  contributes_to_molecular_function:
    id: GO:0042500
    label: aspartic endopeptidase activity, intramembrane cleaving
  description: APH1A is an essential non-catalytic gamma-secretase subunit that helps 
    assemble and stabilize the APH1A-containing presenilin/nicastrin/PSENEN complex, 
    enabling presenilin-dependent intramembrane cleavage of APP, Notch receptors, and 
    related membrane substrates.
  directly_involved_in:
  - id: GO:0031293
    label: membrane protein intracellular domain proteolysis
  - id: GO:0007220
    label: Notch receptor processing
  - id: GO:0042987
    label: amyloid precursor protein catabolic process
  - id: GO:0034205
    label: amyloid-beta formation
  - id: GO:0016485
    label: protein processing
  locations:
  - id: GO:0005789
    label: endoplasmic reticulum membrane
  - id: GO:0032580
    label: Golgi cisterna membrane
  - id: GO:0000139
    label: Golgi membrane
  - id: GO:0010008
    label: endosome membrane
  - id: GO:0016020
    label: membrane
  in_complex:
    id: GO:0070765
    label: gamma-secretase complex
  supported_by:
  - reference_id: PMID:12297508
    supporting_text: physically associates with nicastrin and the heterodimers of the 
      presenilin
  - reference_id: PMID:12297508
    supporting_text: mAPH-1 is probably a functional component of the gamma-secretase 
      complex required for the intramembrane proteolysis of APP and Notch
  - reference_id: PMID:12763021
    supporting_text: APH1a, APH1b, PEN2, and Nicastrin proteins, which are part of the 
      gamma-secretase complex with PS1
  - reference_id: PMID:12763021
    supporting_text: these components are essential for gamma-secretase activity
  - reference_id: PMID:25043039
    supporting_text: 'The Ξ³-secretase complex consists of four components: presenilin, Pen-2,
      Aph-1, and Nicastrin'
  - reference_id: PMID:25043039
    supporting_text: Cleavage of the substrate APP-C100 was blocked by the specific
      inhibitor III-31C
  - reference_id: file:human/APH1A/APH1A-deep-research-falcon.md
    supporting_text: nicastrin (NCT) and APH1A first associate to form the initial
      subcomplex
proposed_new_terms: []
suggested_questions:
- question: Which APH1A-containing gamma-secretase assemblies operate in ER/cis-Golgi 
    compartments versus later endosomal or cell-surface substrate-processing 
    compartments in human neural and glial cells?
  experts:
  - gamma-secretase complex experts
  - Notch and APP processing experts
- question: How should GO distinguish APH1A adaptor/assembly activity from APH1A 
    contribution to presenilin catalytic activity within gamma-secretase?
  experts:
  - GO molecular-function curators
  - gamma-secretase structure-function experts
suggested_experiments:
- description: Compare endogenous APH1A and APH1B knockout or isoform-rescue human 
    neural cells for APP, Notch, and other gamma-secretase substrate cleavage in 
    ER/Golgi, endosomal, and plasma-membrane-enriched fractions.
  hypothesis: APH1A-containing complexes have compartment- and substrate-specific roles 
    that are not fully captured by generic gamma-secretase annotations.
  experiment_type: endogenous isoform-rescue substrate-processing assay
- description: Introduce APH1A interface mutations in endogenous cells and quantify 
    presenilin maturation, nicastrin association, complex abundance, and 
    substrate-specific cleavage products.
  hypothesis: APH1A primarily controls gamma-secretase assembly/stability and 
    substrate-processing competence rather than catalysis directly.
  experiment_type: complex assembly and activity assay