NCSTN

UniProt ID: Q92542
Organism: Homo sapiens
Review Status: COMPLETE
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Gene Description

NCSTN encodes nicastrin, a single-pass type I membrane glycoprotein and essential non-catalytic subunit of the gamma-secretase complex. Together with a presenilin catalytic subunit, APH1A or APH1B, and PSENEN/PEN-2, nicastrin forms a membrane-embedded intramembrane protease complex that processes substrates including APP and Notch receptors. Nicastrin contributes to complex assembly, maturation, substrate recruitment or presentation, and endoprotease activity rather than acting as the catalytic aspartyl protease itself. It functions in ER/Golgi/endomembrane, endosomal, and plasma-membrane compartments where gamma-secretase substrates are processed.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0005886 plasma membrane
IBA
GO_REF:0000033
ACCEPT
Summary: A pool of mature gamma-secretase, including nicastrin, resides at the plasma membrane where it cleaves cell-surface substrate C-terminal fragments such as Notch NEXT.
Reason: Core: well-supported site of active gamma-secretase (IDA/TAS/IBA).
GO:0016485 protein processing
IBA
GO_REF:0000033
ACCEPT
Summary: Nicastrin contributes to the proteolytic processing of gamma-secretase substrates (Notch, APP, and other type I membrane proteins) via regulated intramembrane proteolysis.
Reason: Core processing role of the complex (IDA/IMP/IGI/IBA).
GO:0007220 Notch receptor processing
IBA
GO_REF:0000033
ACCEPT
Summary: Nicastrin-containing gamma-secretase performs the regulated intramembrane (S3) cleavage of Notch receptors that releases NICD; nicastrin recognizes the Notch NEXT substrate.
Reason: Core biological process of the complex; nicastrin is essential (IDA/IMP; structure with Notch1).
GO:0012505 endomembrane system
IEA
GO_REF:0000117
ACCEPT
Summary: Nicastrin distributes across the endomembrane system (ER, Golgi, endosomes) reflecting biogenesis, maturation and the multiple sites where gamma-secretase acts.
Reason: Accurate parent-level localization of the complex (IEA).
GO:0016020 membrane
IEA
GO_REF:0000120
ACCEPT
Summary: Nicastrin is a single-pass type I transmembrane glycoprotein; its membrane integration is required for assembly into the membrane-embedded gamma-secretase complex.
Reason: Core localization: confirmed type I membrane protein (IDA/EXP, structures).
GO:0016485 protein processing
IEA
GO_REF:0000120
ACCEPT
Summary: Nicastrin contributes to the proteolytic processing of gamma-secretase substrates (Notch, APP, and other type I membrane proteins) via regulated intramembrane proteolysis.
Reason: Core processing role of the complex (IDA/IMP/IGI/IBA).
GO:0030659 cytoplasmic vesicle membrane
IEA
GO_REF:0000044
ACCEPT
Summary: UniProt annotates nicastrin as a cytoplasmic vesicle membrane protein, consistent with trafficking of the gamma-secretase complex through the endomembrane/vesicular system.
Reason: Supported by experimental subcellular location (EXP/IEA).
GO:0042470 melanosome
IEA
GO_REF:0000044
KEEP AS NON CORE
Summary: Nicastrin was identified by mass spectrometry in melanosome fractions; this reflects shared endomembrane trafficking rather than a melanosome-specific role.
Reason: Proteomic large-scale localization, non-core (IEA/SubCell).
GO:0099503 secretory vesicle
IEA
GO_REF:0000117
ACCEPT
Summary: Nicastrin associates with secretory vesicle membranes during transport of mature gamma-secretase toward the cell surface.
Reason: Consistent with vesicular trafficking of the complex (IEA).
GO:0005515 protein binding
IPI
PMID:12297508
Mammalian APH-1 interacts with presenilin and nicastrin and ...
MARK AS OVER ANNOTATED
Summary: Generic protein binding is uninformative; nicastrin's meaningful interactions (substrate CTFs, complex subunits) are better captured by adaptor/complex-membership terms.
Reason: Uninformative generic binding; superseded by specific MF/CC terms (IPI).
GO:0005515 protein binding
IPI
PMID:15322109
Both the sequence and length of the C terminus of PEN-2 are ...
MARK AS OVER ANNOTATED
Summary: Generic protein binding is uninformative; nicastrin's meaningful interactions (substrate CTFs, complex subunits) are better captured by adaptor/complex-membership terms.
Reason: Uninformative generic binding; superseded by specific MF/CC terms (IPI).
GO:0005515 protein binding
IPI
PMID:15890777
CD147 is a regulatory subunit of the gamma-secretase complex...
MARK AS OVER ANNOTATED
Summary: Generic protein binding is uninformative; nicastrin's meaningful interactions (substrate CTFs, complex subunits) are better captured by adaptor/complex-membership terms.
Reason: Uninformative generic binding; superseded by specific MF/CC terms (IPI).
GO:0005515 protein binding
IPI
PMID:16641999
TMP21 is a presenilin complex component that modulates gamma...
MARK AS OVER ANNOTATED
Summary: Generic protein binding is uninformative; nicastrin's meaningful interactions (substrate CTFs, complex subunits) are better captured by adaptor/complex-membership terms.
Reason: Uninformative generic binding; superseded by specific MF/CC terms (IPI).
GO:0005515 protein binding
IPI
PMID:18201567
Cellular localization of Nicastrin affects amyloid beta spec...
MARK AS OVER ANNOTATED
Summary: Generic protein binding is uninformative; nicastrin's meaningful interactions (substrate CTFs, complex subunits) are better captured by adaptor/complex-membership terms.
Reason: Uninformative generic binding; superseded by specific MF/CC terms (IPI).
GO:0005515 protein binding
IPI
PMID:19376115
An alternative spliced mouse presenilin-2 mRNA encodes a nov...
MARK AS OVER ANNOTATED
Summary: Generic protein binding is uninformative; nicastrin's meaningful interactions (substrate CTFs, complex subunits) are better captured by adaptor/complex-membership terms.
Reason: Uninformative generic binding; superseded by specific MF/CC terms (IPI).
GO:0005515 protein binding
IPI
PMID:26280335
An atomic structure of human Ξ³-secretase.
MARK AS OVER ANNOTATED
Summary: Generic protein binding is uninformative; nicastrin's meaningful interactions (substrate CTFs, complex subunits) are better captured by adaptor/complex-membership terms.
Reason: Uninformative generic binding; superseded by specific MF/CC terms (IPI).
GO:0005515 protein binding
IPI
PMID:29611543
Intracellular trafficking of TREM2 is regulated by presenili...
MARK AS OVER ANNOTATED
Summary: Generic protein binding is uninformative; nicastrin's meaningful interactions (substrate CTFs, complex subunits) are better captured by adaptor/complex-membership terms.
Reason: Uninformative generic binding; superseded by specific MF/CC terms (IPI).
GO:0005515 protein binding
IPI
PMID:30559186
Bax inhibitor 1 is a Ξ³-secretase-independent presenilin-bind...
MARK AS OVER ANNOTATED
Summary: Generic protein binding is uninformative; nicastrin's meaningful interactions (substrate CTFs, complex subunits) are better captured by adaptor/complex-membership terms.
Reason: Uninformative generic binding; superseded by specific MF/CC terms (IPI).
GO:0004175 endopeptidase activity
IEA
GO_REF:0000107
MARK AS OVER ANNOTATED
Summary: Generic endopeptidase activity is incorrectly attributed to nicastrin, which lacks catalytic residues; proteolysis is performed by the presenilin subunit of gamma-secretase.
Reason: Non-catalytic subunit; activity is presenilin's (IEA).
GO:0005764 lysosome
IEA
GO_REF:0000120
ACCEPT
Summary: Nicastrin is detected in the lysosomal compartment consistent with trafficking of gamma-secretase through the late endolysosomal pathway.
Reason: Consistent with endolysosomal pool of the complex (IEA).
GO:0005765 lysosomal membrane
IEA
GO_REF:0000107
ACCEPT
Summary: Mature gamma-secretase, including nicastrin, reaches lysosomal/late-endosomal membranes, a documented compartment for substrate processing and turnover.
Reason: Supported lysosomal membrane localization (HDA/IEA).
GO:0005769 early endosome
IEA
GO_REF:0000107
ACCEPT
Summary: Active gamma-secretase, including nicastrin, localizes to early endosomes, an important site of APP processing and amyloid-beta generation.
Reason: Endosomal pool is a recognized site of complex activity (IEA).
GO:0005783 endoplasmic reticulum
IEA
GO_REF:0000107
ACCEPT
Summary: Nicastrin is synthesized and initially N-glycosylated in the ER, where immature gamma-secretase subassembly begins before trafficking and maturation.
Reason: Core: ER is the biogenesis/assembly compartment (IDA).
GO:0005794 Golgi apparatus
IEA
GO_REF:0000107
ACCEPT
Summary: Nicastrin transits the Golgi where it undergoes complex N-glycan maturation, a hallmark of the catalytically competent mature gamma-secretase.
Reason: Maturation compartment for nicastrin glycosylation (IDA).
GO:0005886 plasma membrane
IEA
GO_REF:0000120
ACCEPT
Summary: A pool of mature gamma-secretase, including nicastrin, resides at the plasma membrane where it cleaves cell-surface substrate C-terminal fragments such as Notch NEXT.
Reason: Core: well-supported site of active gamma-secretase (IDA/TAS/IBA).
GO:0008021 synaptic vesicle
IEA
GO_REF:0000120
KEEP AS NON CORE
Summary: Synaptic vesicle localization is an electronic, neuron-specific annotation reflecting vesicular trafficking, not a defining gamma-secretase location.
Reason: Specialized neuronal localization, non-core (IEA).
GO:0008233 peptidase activity
IEA
GO_REF:0000107
MARK AS OVER ANNOTATED
Summary: Nicastrin has no peptidase activity despite a degenerate M28 aminopeptidase-like fold; the catalytic site is degenerate and proteolysis resides in presenilin.
Reason: Pseudo-protease fold; no catalytic activity in NCSTN (IEA).
GO:0021549 cerebellum development
IEA
GO_REF:0000107
KEEP AS NON CORE
Summary: Gamma-secretase/Notch signaling influences cerebellar development; this is a downstream developmental consequence rather than nicastrin's direct molecular role.
Reason: Downstream developmental process via Notch, non-core (IEA).
GO:0032991 protein-containing complex
IEA
GO_REF:0000120
ACCEPT
Summary: Nicastrin functions only as part of a hetero-oligomeric assembly; this generic complex term is subsumed by the specific gamma-secretase complex annotation.
Reason: True but generic; the specific gamma-secretase complex term is preferred (IEA).
GO:0042383 sarcolemma
IEA
GO_REF:0000107
KEEP AS NON CORE
Summary: Sarcolemma (muscle plasma membrane) localization is an electronic tissue-specific annotation, a specialization of the general plasma-membrane pool.
Reason: Tissue-specific plasma-membrane subtype, non-core (IEA).
GO:0042500 aspartic endopeptidase activity, intramembrane cleaving
IEA
GO_REF:0000107
MARK AS OVER ANNOTATED
Summary: Intramembrane aspartyl-protease activity is the function of presenilin, not nicastrin; nicastrin is catalytically inactive and only recognizes substrate. The activity belongs to the complex/PSEN.
Reason: NCSTN is non-catalytic; this MF belongs to presenilin (IEA, electronic).
GO:0042734 presynaptic membrane
IEA
GO_REF:0000107
KEEP AS NON CORE
Summary: Electronic annotation places nicastrin at the presynaptic membrane, consistent with neuronal gamma-secretase activity but a specialized, non-core localization.
Reason: Tissue-specialized localization, non-core (IEA).
GO:0070765 gamma-secretase complex
IEA
GO_REF:0000107
ACCEPT
Summary: Nicastrin is an obligate, structurally-defined subunit of the gamma-secretase complex (PSEN1/2, NCSTN, APH1A/B, PSENEN), confirmed by cryo-EM; this is its defining cellular localization.
Reason: Core: NCSTN is a constitutive component of this complex (IDA/IPI, multiple cryo-EM structures).
GO:0097060 synaptic membrane
IEA
GO_REF:0000107
KEEP AS NON CORE
Summary: Synaptic-membrane localization reflects neuronal gamma-secretase processing of synaptic substrates; a specialized site rather than the core annotation.
Reason: Neuronal specialized localization, non-core (IEA).
GO:0005789 endoplasmic reticulum membrane
NAS
PMID:15274632
Purification and characterization of the human gamma-secreta...
ACCEPT
Summary: As a membrane protein, nicastrin resides in the ER membrane during early biogenesis and partial complex assembly prior to Golgi maturation.
Reason: Core-consistent ER membrane localization (NAS, ComplexPortal).
GO:0005886 plasma membrane
IDA
PMID:15274632
Purification and characterization of the human gamma-secreta...
ACCEPT
Summary: A pool of mature gamma-secretase, including nicastrin, resides at the plasma membrane where it cleaves cell-surface substrate C-terminal fragments such as Notch NEXT.
Reason: Core: well-supported site of active gamma-secretase (IDA/TAS/IBA).
GO:0007220 Notch receptor processing
NAS
PMID:10206645
A presenilin-1-dependent gamma-secretase-like protease media...
ACCEPT
Summary: Nicastrin-containing gamma-secretase performs the regulated intramembrane (S3) cleavage of Notch receptors that releases NICD; nicastrin recognizes the Notch NEXT substrate.
Reason: Core biological process of the complex; nicastrin is essential (IDA/IMP; structure with Notch1).
GO:0031293 membrane protein intracellular domain proteolysis
IDA
PMID:15274632
Purification and characterization of the human gamma-secreta...
ACCEPT
Summary: Gamma-secretase, via nicastrin substrate recognition, releases intracellular domains (e.g., NICD, AICD) by intramembrane cleavage of type I membrane substrates.
Reason: Core: ICD-releasing regulated intramembrane proteolysis (IDA, ComplexPortal).
GO:0042987 amyloid precursor protein catabolic process
IDA
PMID:15274632
Purification and characterization of the human gamma-secreta...
ACCEPT
Summary: Nicastrin engages APP C-terminal fragments (C83/C99) for gamma-secretase cleavage, driving the catabolic intramembrane processing of APP.
Reason: Core: complex-mediated APP catabolism, nicastrin binds the CTFs (IDA/IGI/TAS).
GO:0070765 gamma-secretase complex
IPI
PMID:26280335
An atomic structure of human Ξ³-secretase.
ACCEPT
Summary: Nicastrin is an obligate, structurally-defined subunit of the gamma-secretase complex (PSEN1/2, NCSTN, APH1A/B, PSENEN), confirmed by cryo-EM; this is its defining cellular localization.
Reason: Core: NCSTN is a constitutive component of this complex (IDA/IPI, multiple cryo-EM structures).
GO:0000139 Golgi membrane
NAS
PMID:15274632
Purification and characterization of the human gamma-secreta...
ACCEPT
Summary: Membrane-embedded nicastrin localizes to the Golgi membrane during glycan maturation and trafficking of the assembling complex.
Reason: Consistent with Golgi maturation of the complex (NAS, ComplexPortal).
GO:0061133 endopeptidase activator activity
IMP
PMID:12297508
Mammalian APH-1 interacts with presenilin and nicastrin and ...
ACCEPT
Summary: By recruiting and presenting substrate CTFs and stabilizing the mature complex, nicastrin is required for and potentiates presenilin endopeptidase activity within gamma-secretase.
Reason: Core: nicastrin enables/activates complex protease activity (IMP/IGI).
GO:0061133 endopeptidase activator activity
IGI
PMID:12763021
APH1, PEN2, and Nicastrin increase Abeta levels and gamma-se...
ACCEPT
Summary: By recruiting and presenting substrate CTFs and stabilizing the mature complex, nicastrin is required for and potentiates presenilin endopeptidase activity within gamma-secretase.
Reason: Core: nicastrin enables/activates complex protease activity (IMP/IGI).
GO:0016020 membrane
EXP
PMID:25918421
Structural basis of human Ξ³-secretase assembly.
ACCEPT
Summary: Nicastrin is a single-pass type I transmembrane glycoprotein; its membrane integration is required for assembly into the membrane-embedded gamma-secretase complex.
Reason: Core localization: confirmed type I membrane protein (IDA/EXP, structures).
GO:0016020 membrane
EXP
PMID:26623517
Sampling the conformational space of the catalytic subunit o...
ACCEPT
Summary: Nicastrin is a single-pass type I transmembrane glycoprotein; its membrane integration is required for assembly into the membrane-embedded gamma-secretase complex.
Reason: Core localization: confirmed type I membrane protein (IDA/EXP, structures).
GO:0016020 membrane
EXP
PMID:26776682
Structure of the transmembrane domain of human nicastrin-a c...
ACCEPT
Summary: Nicastrin is a single-pass type I transmembrane glycoprotein; its membrane integration is required for assembly into the membrane-embedded gamma-secretase complex.
Reason: Core localization: confirmed type I membrane protein (IDA/EXP, structures).
GO:0030659 cytoplasmic vesicle membrane
EXP
PMID:10993067
Nicastrin modulates presenilin-mediated notch/glp-1 signal t...
ACCEPT
Summary: UniProt annotates nicastrin as a cytoplasmic vesicle membrane protein, consistent with trafficking of the gamma-secretase complex through the endomembrane/vesicular system.
Reason: Supported by experimental subcellular location (EXP/IEA).
GO:0030674 protein-macromolecule adaptor activity
IMP
PMID:12297508
Mammalian APH-1 interacts with presenilin and nicastrin and ...
ACCEPT
Summary: Nicastrin's large ectodomain acts as the substrate-recognition module of gamma-secretase, engaging the N-terminal stub of substrate CTFs and bridging them to the presenilin catalytic core.
Reason: Core MF: nicastrin is the substrate-recognition/adaptor subunit (IMP/IGI; cryo-EM).
GO:0030674 protein-macromolecule adaptor activity
IGI
PMID:12763021
APH1, PEN2, and Nicastrin increase Abeta levels and gamma-se...
ACCEPT
Summary: Nicastrin's large ectodomain acts as the substrate-recognition module of gamma-secretase, engaging the N-terminal stub of substrate CTFs and bridging them to the presenilin catalytic core.
Reason: Core MF: nicastrin is the substrate-recognition/adaptor subunit (IMP/IGI; cryo-EM).
GO:0007220 Notch receptor processing
IMP
PMID:12297508
Mammalian APH-1 interacts with presenilin and nicastrin and ...
ACCEPT
Summary: Nicastrin-containing gamma-secretase performs the regulated intramembrane (S3) cleavage of Notch receptors that releases NICD; nicastrin recognizes the Notch NEXT substrate.
Reason: Core biological process of the complex; nicastrin is essential (IDA/IMP; structure with Notch1).
GO:0007220 Notch receptor processing
IDA
PMID:27608597
Specific combinations of presenilins and Aph1s affect the su...
ACCEPT
Summary: Nicastrin-containing gamma-secretase performs the regulated intramembrane (S3) cleavage of Notch receptors that releases NICD; nicastrin recognizes the Notch NEXT substrate.
Reason: Core biological process of the complex; nicastrin is essential (IDA/IMP; structure with Notch1).
GO:0016485 protein processing
IMP
PMID:12297508
Mammalian APH-1 interacts with presenilin and nicastrin and ...
ACCEPT
Summary: Nicastrin contributes to the proteolytic processing of gamma-secretase substrates (Notch, APP, and other type I membrane proteins) via regulated intramembrane proteolysis.
Reason: Core processing role of the complex (IDA/IMP/IGI/IBA).
GO:0016485 protein processing
IGI
PMID:12763021
APH1, PEN2, and Nicastrin increase Abeta levels and gamma-se...
ACCEPT
Summary: Nicastrin contributes to the proteolytic processing of gamma-secretase substrates (Notch, APP, and other type I membrane proteins) via regulated intramembrane proteolysis.
Reason: Core processing role of the complex (IDA/IMP/IGI/IBA).
GO:0016485 protein processing
IDA
PMID:27608597
Specific combinations of presenilins and Aph1s affect the su...
ACCEPT
Summary: Nicastrin contributes to the proteolytic processing of gamma-secretase substrates (Notch, APP, and other type I membrane proteins) via regulated intramembrane proteolysis.
Reason: Core processing role of the complex (IDA/IMP/IGI/IBA).
GO:0034205 amyloid-beta formation
IMP
PMID:12297508
Mammalian APH-1 interacts with presenilin and nicastrin and ...
ACCEPT
Summary: Gamma-secretase cleavage of APP C99, dependent on nicastrin-mediated substrate recognition, generates amyloid-beta peptides; a central, well-defined activity.
Reason: Core APP-processing output of the complex (IDA/IMP/IGI).
GO:0034205 amyloid-beta formation
IGI
PMID:12763021
APH1, PEN2, and Nicastrin increase Abeta levels and gamma-se...
ACCEPT
Summary: Gamma-secretase cleavage of APP C99, dependent on nicastrin-mediated substrate recognition, generates amyloid-beta peptides; a central, well-defined activity.
Reason: Core APP-processing output of the complex (IDA/IMP/IGI).
GO:0034205 amyloid-beta formation
IDA
PMID:27608597
Specific combinations of presenilins and Aph1s affect the su...
ACCEPT
Summary: Gamma-secretase cleavage of APP C99, dependent on nicastrin-mediated substrate recognition, generates amyloid-beta peptides; a central, well-defined activity.
Reason: Core APP-processing output of the complex (IDA/IMP/IGI).
GO:0042987 amyloid precursor protein catabolic process
IGI
PMID:12763021
APH1, PEN2, and Nicastrin increase Abeta levels and gamma-se...
ACCEPT
Summary: Nicastrin engages APP C-terminal fragments (C83/C99) for gamma-secretase cleavage, driving the catabolic intramembrane processing of APP.
Reason: Core: complex-mediated APP catabolism, nicastrin binds the CTFs (IDA/IGI/TAS).
GO:0042987 amyloid precursor protein catabolic process
IDA
PMID:27608597
Specific combinations of presenilins and Aph1s affect the su...
ACCEPT
Summary: Nicastrin engages APP C-terminal fragments (C83/C99) for gamma-secretase cleavage, driving the catabolic intramembrane processing of APP.
Reason: Core: complex-mediated APP catabolism, nicastrin binds the CTFs (IDA/IGI/TAS).
GO:0070765 gamma-secretase complex
IDA
PMID:12297508
Mammalian APH-1 interacts with presenilin and nicastrin and ...
ACCEPT
Summary: Nicastrin is an obligate, structurally-defined subunit of the gamma-secretase complex (PSEN1/2, NCSTN, APH1A/B, PSENEN), confirmed by cryo-EM; this is its defining cellular localization.
Reason: Core: NCSTN is a constitutive component of this complex (IDA/IPI, multiple cryo-EM structures).
GO:0070765 gamma-secretase complex
IGI
PMID:12763021
APH1, PEN2, and Nicastrin increase Abeta levels and gamma-se...
ACCEPT
Summary: Nicastrin is an obligate, structurally-defined subunit of the gamma-secretase complex (PSEN1/2, NCSTN, APH1A/B, PSENEN), confirmed by cryo-EM; this is its defining cellular localization.
Reason: Core: NCSTN is a constitutive component of this complex (IDA/IPI, multiple cryo-EM structures).
GO:0005515 protein binding
IPI
PMID:26094765
Proton myo-inositol cotransporter is a novel Ξ³-secretase ass...
MARK AS OVER ANNOTATED
Summary: Generic protein binding is uninformative; nicastrin's meaningful interactions (substrate CTFs, complex subunits) are better captured by adaptor/complex-membership terms.
Reason: Uninformative generic binding; superseded by specific MF/CC terms (IPI).
GO:0051117 ATPase binding
IPI
PMID:26094765
Proton myo-inositol cotransporter is a novel Ξ³-secretase ass...
KEEP AS NON CORE
Summary: A specific physical interaction of nicastrin with an ATPase; a documented partner binding but peripheral to its core substrate-recognition role in gamma-secretase.
Reason: Specific partner binding, peripheral to core function (IPI).
GO:0070851 growth factor receptor binding
IPI
PMID:26094765
Proton myo-inositol cotransporter is a novel Ξ³-secretase ass...
KEEP AS NON CORE
Summary: Nicastrin binds a growth factor receptor in a specific assay; consistent with gamma-secretase engaging receptor substrates but not its defining molecular function.
Reason: Specific partner binding, non-core (IPI).
GO:0070765 gamma-secretase complex
NAS
PMID:22086926
Down-regulation of the ATP-binding cassette transporter 2 (A...
ACCEPT
Summary: Nicastrin is an obligate, structurally-defined subunit of the gamma-secretase complex (PSEN1/2, NCSTN, APH1A/B, PSENEN), confirmed by cryo-EM; this is its defining cellular localization.
Reason: Core: NCSTN is a constitutive component of this complex (IDA/IPI, multiple cryo-EM structures).
GO:0010008 endosome membrane
TAS
Reactome:R-HSA-9010096
ACCEPT
Summary: Nicastrin is present in endosomal membranes where the gamma-secretase complex cleaves internalized substrates such as APP-CTFs.
Reason: Endosomal membrane is an active site of the complex (TAS, Reactome).
GO:0016020 membrane
IDA
PMID:25043039
Three-dimensional structure of human Ξ³-secretase.
ACCEPT
Summary: Nicastrin is a single-pass type I transmembrane glycoprotein; its membrane integration is required for assembly into the membrane-embedded gamma-secretase complex.
Reason: Core localization: confirmed type I membrane protein (IDA/EXP, structures).
GO:0016020 membrane
IDA
PMID:26280335
An atomic structure of human Ξ³-secretase.
ACCEPT
Summary: Nicastrin is a single-pass type I transmembrane glycoprotein; its membrane integration is required for assembly into the membrane-embedded gamma-secretase complex.
Reason: Core localization: confirmed type I membrane protein (IDA/EXP, structures).
GO:0034205 amyloid-beta formation
IMP
PMID:25043039
Three-dimensional structure of human Ξ³-secretase.
ACCEPT
Summary: Gamma-secretase cleavage of APP C99, dependent on nicastrin-mediated substrate recognition, generates amyloid-beta peptides; a central, well-defined activity.
Reason: Core APP-processing output of the complex (IDA/IMP/IGI).
GO:0034205 amyloid-beta formation
IMP
PMID:26280335
An atomic structure of human Ξ³-secretase.
ACCEPT
Summary: Gamma-secretase cleavage of APP C99, dependent on nicastrin-mediated substrate recognition, generates amyloid-beta peptides; a central, well-defined activity.
Reason: Core APP-processing output of the complex (IDA/IMP/IGI).
GO:0042982 amyloid precursor protein metabolic process
IDA
PMID:25043039
Three-dimensional structure of human Ξ³-secretase.
ACCEPT
Summary: Nicastrin participates in APP metabolism as the substrate-recognition subunit presenting APP-CTFs to the gamma-secretase catalytic core.
Reason: Core APP-processing role (IDA).
GO:0042982 amyloid precursor protein metabolic process
IDA
PMID:26280335
An atomic structure of human Ξ³-secretase.
ACCEPT
Summary: Nicastrin participates in APP metabolism as the substrate-recognition subunit presenting APP-CTFs to the gamma-secretase catalytic core.
Reason: Core APP-processing role (IDA).
GO:0070765 gamma-secretase complex
IDA
PMID:25043039
Three-dimensional structure of human Ξ³-secretase.
ACCEPT
Summary: Nicastrin is an obligate, structurally-defined subunit of the gamma-secretase complex (PSEN1/2, NCSTN, APH1A/B, PSENEN), confirmed by cryo-EM; this is its defining cellular localization.
Reason: Core: NCSTN is a constitutive component of this complex (IDA/IPI, multiple cryo-EM structures).
GO:0070765 gamma-secretase complex
IDA
PMID:26280335
An atomic structure of human Ξ³-secretase.
ACCEPT
Summary: Nicastrin is an obligate, structurally-defined subunit of the gamma-secretase complex (PSEN1/2, NCSTN, APH1A/B, PSENEN), confirmed by cryo-EM; this is its defining cellular localization.
Reason: Core: NCSTN is a constitutive component of this complex (IDA/IPI, multiple cryo-EM structures).
GO:0035577 azurophil granule membrane
TAS
Reactome:R-HSA-6798739
KEEP AS NON CORE
Summary: Nicastrin is annotated to the azurophil (neutrophil) granule membrane via neutrophil-degranulation pathways; a tissue-specific localization, not the core complex function.
Reason: Pathway/tissue-specific secondary localization (TAS, Reactome).
GO:0005925 focal adhesion
HDA
PMID:21423176
Analysis of the myosin-II-responsive focal adhesion proteome...
KEEP AS NON CORE
Summary: Nicastrin appears in focal adhesion proteomic fractions; this is a co-fractionation/contextual finding, not an established gamma-secretase function site.
Reason: Secondary proteomics localization, non-core (HDA).
GO:0016020 membrane
HDA
PMID:19946888
Defining the membrane proteome of NK cells.
ACCEPT
Summary: Nicastrin is a single-pass type I transmembrane glycoprotein; its membrane integration is required for assembly into the membrane-embedded gamma-secretase complex.
Reason: Core localization: confirmed type I membrane protein (IDA/EXP, structures).
GO:0070062 extracellular exosome
HDA
PMID:19056867
Large-scale proteomics and phosphoproteomics of urinary exos...
KEEP AS NON CORE
Summary: Nicastrin is recovered in exosome proteomes, likely reflecting membrane trafficking and secretion rather than a dedicated exosomal function of gamma-secretase.
Reason: Proteomics-derived secondary localization, not core (HDA).
GO:0005765 lysosomal membrane
HDA
PMID:17897319
Integral and associated lysosomal membrane proteins.
ACCEPT
Summary: Mature gamma-secretase, including nicastrin, reaches lysosomal/late-endosomal membranes, a documented compartment for substrate processing and turnover.
Reason: Supported lysosomal membrane localization (HDA/IEA).
GO:0070062 extracellular exosome
HDA
PMID:20458337
MHC class II-associated proteins in B-cell exosomes and pote...
KEEP AS NON CORE
Summary: Nicastrin is recovered in exosome proteomes, likely reflecting membrane trafficking and secretion rather than a dedicated exosomal function of gamma-secretase.
Reason: Proteomics-derived secondary localization, not core (HDA).
GO:0005886 plasma membrane
TAS
Reactome:R-HSA-1251997
ACCEPT
Summary: A pool of mature gamma-secretase, including nicastrin, resides at the plasma membrane where it cleaves cell-surface substrate C-terminal fragments such as Notch NEXT.
Reason: Core: well-supported site of active gamma-secretase (IDA/TAS/IBA).
GO:0005886 plasma membrane
TAS
Reactome:R-HSA-193682
ACCEPT
Summary: A pool of mature gamma-secretase, including nicastrin, resides at the plasma membrane where it cleaves cell-surface substrate C-terminal fragments such as Notch NEXT.
Reason: Core: well-supported site of active gamma-secretase (IDA/TAS/IBA).
GO:0005886 plasma membrane
TAS
Reactome:R-HSA-205112
ACCEPT
Summary: A pool of mature gamma-secretase, including nicastrin, resides at the plasma membrane where it cleaves cell-surface substrate C-terminal fragments such as Notch NEXT.
Reason: Core: well-supported site of active gamma-secretase (IDA/TAS/IBA).
GO:0005886 plasma membrane
TAS
Reactome:R-HSA-2220988
ACCEPT
Summary: A pool of mature gamma-secretase, including nicastrin, resides at the plasma membrane where it cleaves cell-surface substrate C-terminal fragments such as Notch NEXT.
Reason: Core: well-supported site of active gamma-secretase (IDA/TAS/IBA).
GO:0005886 plasma membrane
TAS
Reactome:R-HSA-3928656
ACCEPT
Summary: A pool of mature gamma-secretase, including nicastrin, resides at the plasma membrane where it cleaves cell-surface substrate C-terminal fragments such as Notch NEXT.
Reason: Core: well-supported site of active gamma-secretase (IDA/TAS/IBA).
GO:0005886 plasma membrane
TAS
Reactome:R-HSA-6798739
ACCEPT
Summary: A pool of mature gamma-secretase, including nicastrin, resides at the plasma membrane where it cleaves cell-surface substrate C-terminal fragments such as Notch NEXT.
Reason: Core: well-supported site of active gamma-secretase (IDA/TAS/IBA).
GO:0005886 plasma membrane
TAS
Reactome:R-HSA-9013361
ACCEPT
Summary: A pool of mature gamma-secretase, including nicastrin, resides at the plasma membrane where it cleaves cell-surface substrate C-terminal fragments such as Notch NEXT.
Reason: Core: well-supported site of active gamma-secretase (IDA/TAS/IBA).
GO:0005886 plasma membrane
TAS
Reactome:R-HSA-9017817
ACCEPT
Summary: A pool of mature gamma-secretase, including nicastrin, resides at the plasma membrane where it cleaves cell-surface substrate C-terminal fragments such as Notch NEXT.
Reason: Core: well-supported site of active gamma-secretase (IDA/TAS/IBA).
GO:0005886 plasma membrane
TAS
Reactome:R-HSA-9839376
ACCEPT
Summary: A pool of mature gamma-secretase, including nicastrin, resides at the plasma membrane where it cleaves cell-surface substrate C-terminal fragments such as Notch NEXT.
Reason: Core: well-supported site of active gamma-secretase (IDA/TAS/IBA).
GO:0005886 plasma membrane
TAS
Reactome:R-NUL-2197556
ACCEPT
Summary: A pool of mature gamma-secretase, including nicastrin, resides at the plasma membrane where it cleaves cell-surface substrate C-terminal fragments such as Notch NEXT.
Reason: Core: well-supported site of active gamma-secretase (IDA/TAS/IBA).
GO:0005886 plasma membrane
TAS
Reactome:R-NUL-9604300
ACCEPT
Summary: A pool of mature gamma-secretase, including nicastrin, resides at the plasma membrane where it cleaves cell-surface substrate C-terminal fragments such as Notch NEXT.
Reason: Core: well-supported site of active gamma-secretase (IDA/TAS/IBA).
GO:0005783 endoplasmic reticulum
IDA
PMID:15274632
Purification and characterization of the human gamma-secreta...
ACCEPT
Summary: Nicastrin is synthesized and initially N-glycosylated in the ER, where immature gamma-secretase subassembly begins before trafficking and maturation.
Reason: Core: ER is the biogenesis/assembly compartment (IDA).
GO:0005794 Golgi apparatus
IDA
PMID:15274632
Purification and characterization of the human gamma-secreta...
ACCEPT
Summary: Nicastrin transits the Golgi where it undergoes complex N-glycan maturation, a hallmark of the catalytically competent mature gamma-secretase.
Reason: Maturation compartment for nicastrin glycosylation (IDA).
GO:0006509 membrane protein ectodomain proteolysis
IDA
PMID:15274632
Purification and characterization of the human gamma-secreta...
MODIFY
Summary: Gamma-secretase performs intramembrane/intracellular-domain cleavage, not ectodomain shedding (the latter is done by alpha/beta-secretases); the intramembrane proteolysis term is more accurate.
Reason: Mislabeled granularity: NCSTN/gamma-secretase does intramembrane, not ectodomain, proteolysis (IDA).
GO:0007220 Notch receptor processing
TAS
PMID:15274632
Purification and characterization of the human gamma-secreta...
ACCEPT
Summary: Nicastrin-containing gamma-secretase performs the regulated intramembrane (S3) cleavage of Notch receptors that releases NICD; nicastrin recognizes the Notch NEXT substrate.
Reason: Core biological process of the complex; nicastrin is essential (IDA/IMP; structure with Notch1).
GO:0016485 protein processing
IDA
PMID:15274632
Purification and characterization of the human gamma-secreta...
ACCEPT
Summary: Nicastrin contributes to the proteolytic processing of gamma-secretase substrates (Notch, APP, and other type I membrane proteins) via regulated intramembrane proteolysis.
Reason: Core processing role of the complex (IDA/IMP/IGI/IBA).
GO:0042987 amyloid precursor protein catabolic process
TAS
PMID:15274632
Purification and characterization of the human gamma-secreta...
ACCEPT
Summary: Nicastrin engages APP C-terminal fragments (C83/C99) for gamma-secretase cleavage, driving the catabolic intramembrane processing of APP.
Reason: Core: complex-mediated APP catabolism, nicastrin binds the CTFs (IDA/IGI/TAS).
GO:0006508 proteolysis
NAS
PMID:10993067
Nicastrin modulates presenilin-mediated notch/glp-1 signal t...
MODIFY
Summary: Generic proteolysis under-specifies the role; gamma-secretase performs regulated intramembrane (within-membrane) proteolysis of its substrates.
Reason: Too general; a specific intramembrane proteolysis child applies (NAS).
Proposed replacements: membrane protein proteolysis
GO:0016020 membrane
NAS
PMID:10993067
Nicastrin modulates presenilin-mediated notch/glp-1 signal t...
ACCEPT
Summary: Nicastrin is a single-pass type I transmembrane glycoprotein; its membrane integration is required for assembly into the membrane-embedded gamma-secretase complex.
Reason: Core localization: confirmed type I membrane protein (IDA/EXP, structures).

Core Functions

NCSTN is an essential non-catalytic gamma-secretase subunit that helps assemble and position the substrate-recognition extracellular domain of the complex, enabling presenilin-dependent intramembrane cleavage of APP, Notch receptors, and related substrates.

Supporting Evidence:
  • PMID:10993067
    Nicastrin, a transmembrane glycoprotein, forms high molecular weight complexes with presenilin 1 and presenilin 2
  • PMID:10993067
    functional components of a multimeric complex necessary for the intramembranous proteolysis of proteins such as Notch/GLP-1 and betaAPP
  • PMID:25043039
    The Ξ³-secretase complex consists of four components: presenilin, Pen-2, Aph-1, and Nicastrin
  • PMID:25043039
    Nicastrin contains a large extracellular domain that is thought to be responsible for substrate recruitment
  • PMID:12297508
    mAPH-1 is probably a functional component of the gamma-secretase complex required for the intramembrane proteolysis of APP and Notch

References

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Suggested Questions for Experts

Q: How should GO distinguish NCSTN substrate-recognition/adaptor activity from the catalytic presenilin intramembrane aspartyl protease activity within gamma-secretase?

Suggested experts: gamma-secretase structural biology experts, GO molecular-function curators

Q: Which NCSTN-dependent gamma-secretase locations are physiologically active for APP versus Notch processing in vivo?

Suggested experts: APP trafficking experts, Notch signaling experts

Suggested Experiments

Experiment: Use endogenous NCSTN variants or extracellular-domain mutants in human neurons and Notch reporter cells to separately measure complex assembly, substrate recruitment, APP cleavage, and Notch S3 cleavage.

Hypothesis: NCSTN primarily determines substrate presentation and complex maturation rather than catalytic chemistry.

Type: endogenous gamma-secretase substrate recruitment assay

Experiment: Map active gamma-secretase complexes containing tagged NCSTN across ER, Golgi, endosome, lysosome, and plasma membrane compartments with APP- and Notch-specific reporters.

Hypothesis: APP and Notch processing rely on overlapping but non-identical NCSTN-containing gamma-secretase pools.

Type: compartment-resolved gamma-secretase activity assay

πŸ“š Additional Documentation

Notes

(NCSTN-notes.md)

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