ALS2

UniProt ID: Q96Q42
Organism: Homo sapiens
Review Status: DRAFT
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Gene Description

Alsin, encoded by ALS2, is a multidomain Rab5 guanine-nucleotide exchange factor that promotes endosomal membrane trafficking. The long isoform contains an N-terminal RCC1-like region, central DH/PH domains, MORN motifs and a C-terminal VPS9 domain. Functional self-association and the VPS9-containing region support Rab5 nucleotide exchange and endosome fusion. Cytosolic alsin can be recruited to membrane ruffles and nascent macropinosomes downstream of activated Rac1. Neuronal endosomal and somatodendritic pools connect this trafficking function to neuronal maintenance; recessive loss-of-function variants cause juvenile motor neuron disorders.

Existing Annotations Review

GO Term Evidence Action Reason
IEA
GO_REF:0000107
ACCEPT
Summary: Alsin is recruited to membrane ruffles during Rac1-dependent endocytosis.
Reason: The donor Q920R0 is mouse Als2; the Ensembl protein is the associated source identifier, whose exact historical peptide version was not independently reconstructed. Human evidence now corroborates the compartment: PMID:17409386 Methods explicitly describes human cDNA constructs and Results shows recruitment of endogenous HeLa ALS2 to EGF-induced ruffles. Localization is activation-dependent, not a claim that ALS2 alone initiates a ruffle. The original mouse transfer remains intact.
Propagation Review
Root cause: NO FAILURE CORE
Sources checked:
UniProtKB:Q920R0 · mouse Als2 SUPPORTS TRANSFER
Mouse Als2 is the ortholog source. Independent human ALS2 constructs/endogenous-cell observations corroborate the relevant location; this does not reconstruct every original mouse source row.
ensembl:ENSMUSP00000027178 UNRESOLVED
The machine assertion supplies this mouse Ensembl protein alongside Q920R0; the exact historical peptide version and donor annotation were not separately recovered.
Supporting Evidence:
PMID:17409386
In the cells activated Rac1 recruits cytoplasmic ALS2 to membrane ruffles and subsequently to nascent macropinosomes via Rac1-activated macropinocytosis.
ISS
GO_REF:0000024
ACCEPT
Summary: Ruffle localization is consistent with conserved, regulated alsin recruitment.
Reason: The donor Q920R0 is mouse Als2; the manually curated ortholog transfer is independently corroborated in human cells. Human evidence now corroborates the compartment: PMID:17409386 Methods explicitly describes human cDNA constructs and Results shows recruitment of endogenous HeLa ALS2 to EGF-induced ruffles. Localization is activation-dependent, not a claim that ALS2 alone initiates a ruffle. The original mouse transfer remains intact.
Propagation Review
Root cause: NO FAILURE CORE
Sources checked:
UniProtKB:Q920R0 · mouse Als2 SUPPORTS TRANSFER
Mouse Als2 is the ortholog source. Independent human ALS2 constructs/endogenous-cell observations corroborate the relevant location; this does not reconstruct every original mouse source row.
Supporting Evidence:
PMID:17409386
In the cells activated Rac1 recruits cytoplasmic ALS2 to membrane ruffles and subsequently to nascent macropinosomes via Rac1-activated macropinocytosis.
GO:0005085 guanyl-nucleotide exchange factor activity
IBA
GO_REF:0000033
ACCEPT
Summary: The ancestral GEF annotation agrees with the established Rab5 exchange activity.
Reason: PAINT asserts inheritance from PTN002338289, not a pairwise transfer from the single listed fly gene. FBgn0037116 is Drosophila Als2. The exact IBD placement and alignment were not recovered, so its historical reconstruction remains unresolved; direct ALS2 Rab5 exchange evidence independently supports this broad MF, with no demonstrated target-specific loss. Donor count is not an objection.
Propagation Review
Root cause: NO FAILURE CORE
Sources checked:
FB:FBgn0037116 · Drosophila Als2 UNRESOLVED
Official FlyBase/NCBI identify Drosophila Als2/CG7158. The exact historical experimental row seeding this PAINT node was not reconstructed; target Rab5/endosomal evidence independently corroborates the broad function.
PANTHER:PTN002338289 UNRESOLVED
This is the PAINT ancestral node, not a donor count. Its exact tree/MSA and IBD placement were not recovered; direct target evidence supports the term without establishing or contradicting the historical node placement.
Supporting Evidence:
PMID:12837691
Here we show that the ALS2 protein specifically binds to small GTPase Rab5 and functions as a GEF for Rab5.
GO:0005085 guanyl-nucleotide exchange factor activity
IDA
PMID:12837691
ALS2, a novel guanine nucleotide exchange factor for the sma...
ACCEPT
Summary: ALS2 promotes guanine-nucleotide exchange on Rab5.
Reason: The original abstract explicitly identifies Rab5 binding and nucleotide exchange mediated by the VPS9-containing region. Independent human-construct GDP-release experiments in PMID:15033976 support this activity. The current generic GO:0005085 encompasses the reaction; former Rab-specific GEF identifiers are alternate IDs of this term, so no invented narrower identifier is needed. Full PMID:12837691 Methods were not recovered.
Supporting Evidence:
PMID:12837691
Here we show that the ALS2 protein specifically binds to small GTPase Rab5 and functions as a GEF for Rab5.
PMID:12837691
The carboxy-terminus of ALS2 protein carrying a VPS9 domain mediates not only the activation of Rab5 via a guanine-nucleotide exchanging reaction but also the endosomal localization of the ALS2 protein, while the amino-terminal half containing RLD acts suppressive in its membranous localization.
PMID:15033976
We found that the Vps9p domain of alsin has Rab5 guanine nucleotide exchange activity.
GO:0005085 guanyl-nucleotide exchange factor activity
IDA
PMID:15247254
Homo-oligomerization of ALS2 through its unique carboxyl-ter...
ACCEPT
Summary: Self-associated ALS2 contributes to Rab5 guanine-nucleotide exchange.
Reason: Preserve the original contributes_to qualification. Full PMID:15247254 Methods and Figure 5 measure dissociation of preloaded tritiated GDP from Rab5A with affinity-isolated ALS2 expressed in COS-7 cells. Oligomerization-defective constructs retain Rab5 binding but lose exchange. The study supports a functional oligomeric unit without requiring a particular native stoichiometry.
Supporting Evidence:
PMID:15247254
This homo-oligomerization is crucial for the Rab5GEF activity in vitro and the ALS2-mediated endosome enlargement in the cells.
GO:0005085 guanyl-nucleotide exchange factor activity
IDA
PMID:16049005
ALS2/Alsin regulates Rac-PAK signaling and neurite outgrowth...
UNDECIDED
Summary: Cellular Rac activation does not settle source-specific nucleotide-exchange catalysis.
Reason: PMID:16049005 measures Rac-GTP capture after human ALS2 expression in CHO cells, with a DH-domain requirement, but does not isolate nucleotide exchange. The authors interpret this as Rac-GEF activity; PMID:17409386 instead supports an active-Rac1 effector. This is scientific uncertainty after inspecting the original full article, not a claim that the paper is inaccessible. Retain uncertainty about its catalytic assignment while preserving its positive signaling results. Independent Rab5 exchange experiments support their own GEF rows; they do not resolve the mechanistic interpretation of this IDA source.
Supporting Evidence:
PMID:16049005
Furthermore, ALS2 stimulates Rac but not Rho or Cdc42 activities, and this induces a corresponding increase in PAK1 activity.
GO:0005085 guanyl-nucleotide exchange factor activity
IEA
GO_REF:0000002
ACCEPT
Summary: The broad GEF annotation is correct, with stronger catalytic grounding outside the mapped DH domain.
Reason: IPR000219 is the DH-domain source of this InterPro mapping. Domain membership alone does not resolve direct Rac catalysis, especially given the contrasting Rac assays. Independent human ALS2 VPS9-region Rab5 exchange establishes GO:0005085 for the gene product. Acceptance of that broad activity does not certify the DH domain as the catalytic site for Rab5 or an independently demonstrated Rac GEF.
Propagation Review
Root cause: NO FAILURE CORE
Sources checked:
InterPro:IPR000219 · DH domain UNRESOLVED
The DH-domain mapping suggests GEF activity, but direct Rac exchange is not established by a DH signature. Independent target VPS9-region Rab5 assays establish the generic GEF term.
Supporting Evidence:
PMID:12837691
Here we show that the ALS2 protein specifically binds to small GTPase Rab5 and functions as a GEF for Rab5.
PMID:15033976
We found that the Vps9p domain of alsin has Rab5 guanine nucleotide exchange activity.
GO:0005096 GTPase activator activity
IDA
PMID:12837691
ALS2, a novel guanine nucleotide exchange factor for the sma...
UNDECIDED
Summary: The GTPase-activator annotation requires resolving hydrolysis versus nucleotide exchange in the original experiments.
Reason: Live GO:0005096 denotes increased GTP hydrolysis, whereas the available PMID:12837691 abstract explicitly describes GDP/GTP exchange. That is a serious term-mechanism mismatch, but the original full Methods and any separate hydrolysis assay were not recovered: the located grant-hosted PDF could not be extracted or displayed. Defer to the experimental curator pending that source-specific check; independent GEF evidence is not proof that an uninspected GAP assay was absent.
Supporting Evidence:
PMID:12837691
Here we show that the ALS2 protein specifically binds to small GTPase Rab5 and functions as a GEF for Rab5.
GO:0005096 GTPase activator activity
IDA
PMID:15247254
Homo-oligomerization of ALS2 through its unique carboxyl-ter...
MODIFY
Summary: The directly measured activity is Rab5 nucleotide exchange, not stimulation of GTP hydrolysis.
Reason: Full PMID:15247254 Methods and Figure 5 quantify loss of preloaded tritiated GDP from Rab5A. The results distinguish catalytic exchange from substrate binding; they do not assay GTP hydrolysis. Live GO:0005096 requires stimulation of hydrolysis. Refine this source-specific annotation to GO:0005085, the actual exchange mechanism. This does not assert that every conceivable ALS2 hydrolysis effect has been excluded. The replacement converges on the existing GO:0005085 contribution-to-exchange annotation from this paper; consolidate the biological claim using the existing contributes_to qualifier, without implying that an isolated monomer is sufficient. The original source qualifier is preserved here; this qualifier recommendation applies to the replacement assertion.
Supporting Evidence:
PMID:15247254
This homo-oligomerization is crucial for the Rab5GEF activity in vitro and the ALS2-mediated endosome enlargement in the cells.
GO:0005515 protein binding
IPI
PMID:21300063
Defective relocalization of ALS2/alsin missense mutants to R...
MODIFY
Summary: Rab5 binding has a more informative small-GTPase-binding term.
Reason: The source assertion names RAB5A/P20339. PMID:21300063 is cached only as an abstract, so its exact interaction panel and construct details remain uninspected. Independent PMID:12837691 and the full binding assays in PMID:15247254 directly support ALS2–Rab5 association. Use the existing specific MF GO:0031267; do not infer an unrelated adapter activity from the generic interaction row.
Proposed replacements: small GTPase binding
Supporting Evidence:
PMID:12837691
Here we show that the ALS2 protein specifically binds to small GTPase Rab5 and functions as a GEF for Rab5.
GO:0005515 protein binding
IPI
PMID:33961781
Dual proteome-scale networks reveal cell-specific remodeling...
UNDECIDED
Summary: The ALS2–NEK1 proteome-screen interaction remains source-limited.
Reason: The source names NEK1/Q96PY6. PMID:33961781 describes human ORFeome FLAG-HA affinity-purification mass spectrometry in 293T and HCT116 cells. The canonical extraction is partial; the separate, richer normal-fetch XML body was also read, but neither yields the pair-specific ALS2–NEK1 supplementary hit. Do not turn a screen-level description into verified binary binding, and do not reject the curator because the target is absent from the main article text. No specific MF replacement is established.
GO:0005634 nucleus
IDA
PMID:12837691
ALS2, a novel guanine nucleotide exchange factor for the sma...
UNDECIDED
Summary: The nuclear localization assertion cannot be resolved from the accessible original evidence.
Reason: PMID:12837691 is abstract-only locally and its original nuclear panel/construct conditions were not recovered. Predominant cytosolic or endosomal localization does not disprove a nuclear subpopulation. The separate antibody-defined rat-neuron exclusion in PMID:15371724 is context-limited and cannot overturn this human annotation. Retain uncertainty and defer to the source curator.
GO:0005737 cytoplasm
IBA
GO_REF:0000033
ACCEPT
Summary: A cytoplasmic pool is compatible with ALS2 endosomal exchange and regulated recruitment.
Reason: The PAINT node is PTN002338289, with extant evidence from fly Als2, mouse Als2, mouse Als2cl, rat Als2 and human ALS2. ALS2CL is a paralog, not a mislabeled ALS2 ortholog; its Rab5-binding/endosomal data provide family context. Exact ancestral placement remains unreconstructed. Human ALS2 is normally cytosolic before Rac1-dependent membrane recruitment, independently supporting the broad compartment. The target in WITH/FROM is legitimate experimental grounding, not circular evidence.
Propagation Review
Root cause: NO FAILURE CORE
Sources checked:
FB:FBgn0037116 · Drosophila Als2 UNRESOLVED
Official FlyBase/NCBI identify Drosophila Als2/CG7158. The exact historical experimental row seeding this PAINT node was not reconstructed; target Rab5/endosomal evidence independently corroborates the broad function.
MGI:MGI:1921268 · mouse Als2 UNRESOLVED
Official MGI/MouseMine identify mouse Als2. Mouse-neuron evidence is distinguished from human constructs expressed in rodent cells. Historical PAINT source-row/node placement was not independently reconstructed.
MGI:MGI:2447532 · mouse Als2cl UNRESOLVED
Official MGI identifies Als2cl, an ALS2-related paralog. PMID:15388334 reports Rab5 binding and endosome effects for ALS2CL; its abstract includes human and mouse products but does not resolve every construct-specific assay. This is family evidence, not proof that all ALS2-specific roles are shared.
PANTHER:PTN002338289 UNRESOLVED
This is the PAINT ancestral node, not a donor count. Its exact tree/MSA and IBD placement were not recovered; direct target evidence supports the term without establishing or contradicting the historical node placement.
RGD:1310372 · rat Als2 SUPPORTS TRANSFER
Official NCBI Gene363235 identifies rat Als2 and the RGD identifier. Rodent neuronal localization in PMID:15371724/16049005 supports the relevant compartment, while human somatodendritic localization independently supports the target.
UniProtKB:Q96Q42 · human ALS2 SUPPORTS TRANSFER
The target is a legitimate extant experimental source. Rab5 exchange/binding and human localization papers support the relevant target function; self-inclusion in PAINT is not circular.
Supporting Evidence:
PMID:12837691
The carboxy-terminus of ALS2 protein carrying a VPS9 domain mediates not only the activation of Rab5 via a guanine-nucleotide exchanging reaction but also the endosomal localization of the ALS2 protein, while the amino-terminal half containing RLD acts suppressive in its membranous localization.
PMID:17409386
In the cells activated Rac1 recruits cytoplasmic ALS2 to membrane ruffles and subsequently to nascent macropinosomes via Rac1-activated macropinocytosis.
GO:0005737 cytoplasm
IEA
GO_REF:0000120
ACCEPT
Summary: The combined electronic cytoplasmic annotation agrees with experimental localization.
Reason: The combined source is ARBA00026971 plus mouse Als2 Q920R0 and the listed Ensembl protein. Exact ARBA training conditions and historical peptide version were not reconstructed. Human ALS2 cytosolic-to-membrane recruitment in PMID:17409386 and the original localization work support this broad compartment without assigning a distinct cytoplasmic catalytic process.
Propagation Review
Root cause: NO FAILURE CORE
Sources checked:
ARBA:ARBA00026971 UNRESOLVED
The exact learned rule and training-source chain were not reconstructed; independent human localization supports the broad cytoplasmic target annotation.
UniProtKB:Q920R0 · mouse Als2 SUPPORTS TRANSFER
Mouse Als2 is the ortholog source. Independent human ALS2 constructs/endogenous-cell observations corroborate the relevant location; this does not reconstruct every original mouse source row.
ensembl:ENSMUSP00000027178 UNRESOLVED
The machine assertion supplies this mouse Ensembl protein alongside Q920R0; the exact historical peptide version and donor annotation were not separately recovered.
Supporting Evidence:
PMID:12837691
The carboxy-terminus of ALS2 protein carrying a VPS9 domain mediates not only the activation of Rab5 via a guanine-nucleotide exchanging reaction but also the endosomal localization of the ALS2 protein, while the amino-terminal half containing RLD acts suppressive in its membranous localization.
PMID:17409386
In the cells activated Rac1 recruits cytoplasmic ALS2 to membrane ruffles and subsequently to nascent macropinosomes via Rac1-activated macropinocytosis.
GO:0005769 early endosome
IDA
PMID:12837691
ALS2, a novel guanine nucleotide exchange factor for the sma...
ACCEPT
Summary: Alsin associates with early endosomal compartments.
Reason: The original abstract explicitly reports co-localization with Rab5 and EEA1 and an effect on endosome enlargement. The cell and construct species are not stated in that abstract; human-construct and endogenous-human recruitment studies provide independent support. The annotation is not extrapolated from mitochondrial or Golgi stress phenotypes.
Supporting Evidence:
PMID:12837691
Ectopically expressed ALS2 protein localizes with Rab5 and early endosome antigen-1 (EEA1) onto early endosomal compartments and stimulates the enlargement of endosomes in cultured cortical neurons.
GO:0005813 centrosome
IBA
GO_REF:0000033
KEEP AS NON CORE
Summary: A centrosomal alsin pool is directly supported in human material.
Reason: The IBA descends from PTN002918520 and includes mouse Als2 and human ALS2 among its evidence. Exact ancestral placement was not recovered, but PMID:16085057 reports centrosomal-marker colocalization in human cell lines and endogenous protein in purified human cortical centrosomes. Accept the location at this resolution without inventing a centrosome-specific GEF reaction or microtubule-nucleating activity. Retain this partial centrosomal pool as non-core: the localization is supported, but its contribution to the established endosomal exchange mechanism is not resolved.
Propagation Review
Root cause: NO FAILURE NON CORE
Sources checked:
MGI:MGI:1921268 · mouse Als2 UNRESOLVED
Official MGI/MouseMine identify mouse Als2. Mouse-neuron evidence is distinguished from human constructs expressed in rodent cells. Historical PAINT source-row/node placement was not independently reconstructed.
PANTHER:PTN002918520 UNRESOLVED
This is the PAINT ancestral node, not a donor count. Its exact tree/MSA and IBD placement were not recovered; direct target evidence supports the term without establishing or contradicting the historical node placement.
UniProtKB:Q96Q42 · human ALS2 SUPPORTS TRANSFER
The target is a legitimate extant experimental source. Rab5 exchange/binding and human localization papers support the relevant target function; self-inclusion in PAINT is not circular.
Supporting Evidence:
PMID:16085057
Moreover endogenous Alsin was detected in a centrosome preparation purified from human cortical brain.
GO:0005813 centrosome
IDA
PMID:16085057
Alsin is partially associated with centrosome in human cells...
KEEP AS NON CORE
Summary: A fraction of alsin localizes to human centrosomes.
Reason: The abstract explicitly distinguishes monkey COS-7 overexpression phenotypes from human SW13, LA-N-2 and SK-N-SH centrosomal-marker colocalization and an endogenous human-brain centrosome preparation. Those positive findings support this CC annotation. Full biochemical purity controls were not available; no stronger centrosome-organizing mechanism is inferred. Retain this partial centrosomal pool as non-core: the localization is supported, but its contribution to the established endosomal exchange mechanism is not resolved.
Supporting Evidence:
PMID:16085057
Immunofluorescence staining revealed a colocalization of Alsin with the centrosomal markers gamma-tubulin and A kinase anchoring protein (AKAP-450).
PMID:16085057
Moreover endogenous Alsin was detected in a centrosome preparation purified from human cortical brain.
GO:0005813 centrosome
IEA
GO_REF:0000107
KEEP AS NON CORE
Summary: The ortholog-transferred centrosomal location has independent human evidence.
Reason: The Q920R0 source is mouse Als2; its associated Ensembl peptide version was not independently reconstructed. PMID:16085057 directly supports a partial human centrosomal pool, so missing reconstruction of the historical donor assay is not a reason to discard a correct location. A centrosomal location does not by itself specify what activity occurs there. Retain this partial centrosomal pool as non-core: the localization is supported, but its contribution to the established endosomal exchange mechanism is not resolved.
Propagation Review
Root cause: NO FAILURE NON CORE
Sources checked:
UniProtKB:Q920R0 · mouse Als2 SUPPORTS TRANSFER
Mouse Als2 is the ortholog source. Independent human ALS2 constructs/endogenous-cell observations corroborate the relevant location; this does not reconstruct every original mouse source row.
ensembl:ENSMUSP00000027178 UNRESOLVED
The machine assertion supplies this mouse Ensembl protein alongside Q920R0; the exact historical peptide version and donor annotation were not separately recovered.
Supporting Evidence:
PMID:16085057
Moreover endogenous Alsin was detected in a centrosome preparation purified from human cortical brain.
GO:0005829 cytosol
IDA
PMID:12837691
ALS2, a novel guanine nucleotide exchange factor for the sma...
ACCEPT
Summary: Cytosolic ALS2 supplies a regulated pool for endosomal recruitment.
Reason: The original PMID:12837691 source is retained. Its abstract describes suppression of membrane localization by the N-terminal region; full human-cDNA experiments and endogenous HeLa staining in PMID:17409386 independently demonstrate predominantly cytoplasmic ALS2 and stimulus-dependent membrane redistribution. Accept cytosol without inferring nuclear exclusion.
Supporting Evidence:
PMID:12837691
The carboxy-terminus of ALS2 protein carrying a VPS9 domain mediates not only the activation of Rab5 via a guanine-nucleotide exchanging reaction but also the endosomal localization of the ALS2 protein, while the amino-terminal half containing RLD acts suppressive in its membranous localization.
PMID:17409386
In the cells activated Rac1 recruits cytoplasmic ALS2 to membrane ruffles and subsequently to nascent macropinosomes via Rac1-activated macropinocytosis.
GO:0005829 cytosol
TAS
Reactome:R-HSA-8875320
ACCEPT
Summary: Reactome places the Rab5 exchange machinery on the cytosolic side.
Reason: R-HSA-8875320 describes human RAB5 GEFs, including ALS2-family members, promoting GDP release and allowing GTP binding. This fits the cytosolic ALS2 pool and recruitment to endosomal membranes. It is a pathway synthesis, not an additional independent ALS2 localization assay.
Supporting Evidence:
Reactome:R-HSA-8875320
Interaction of RAB5 with its GEFs promotes release of GDP, allowing GTP to bind, and precludes the interaction of RAB5 with GDI and CHM proteins.
GO:0007032 endosome organization
NAS
PMID:12837691
ALS2, a novel guanine nucleotide exchange factor for the sma...
ACCEPT
Summary: ALS2 contributes a Rab5 exchange step to endosome organization.
Reason: GO:0007032 concerns assembly, arrangement or disassembly of endosomes. ALS2 supplies the exchange activity controlling Rab5-dependent membrane fusion, with domain-dependent effects on endosome enlargement. This is positive mechanistic participation, not merely survival dependence. The original NAS and reference remain unchanged.
Supporting Evidence:
PMID:12837691
Ectopically expressed ALS2 protein localizes with Rab5 and early endosome antigen-1 (EEA1) onto early endosomal compartments and stimulates the enlargement of endosomes in cultured cortical neurons.
PMID:12837691
Further, the DH/PH domain in the middle portion of ALS2 protein enhances the VPS9 domain-mediated endosome fusions.
GO:0007041 lysosomal transport
IDA
PMID:12837691
ALS2, a novel guanine nucleotide exchange factor for the sma...
UNDECIDED
Summary: The specific lysosomal-transport experiment remains unresolved.
Reason: The original PMID:12837691 abstract establishes early-endosome organization, but does not expose the source experiment for transport to lysosomes. The full target panel was not recovered. Later PMID:21300063 supports an endosome–autophagosome fusion context, not by itself every lysosomal cargo route. Preserve the curator assertion with uncertainty rather than treating early-endosomal specialization as a contradiction.
GO:0014069 postsynaptic density
IEA
GO_REF:0000107
KEEP AS NON CORE
Summary: Postsynaptic-density localization is a supported neuronal context of alsin trafficking.
Reason: The automated transfer derives from mouse Als2/Q920R0. Full PMID:17093100 uses mouse ALS2 constructs, mouse brain fractions and primary neurons; it reports PSD enrichment and GRIP1-related distribution. HEK293 coexpression is a host context, not proof of a human ALS2 insert. Retain the conserved neuronal subcompartment as non-core rather than elevating mouse synaptic findings to a universal human catalytic location.
Propagation Review
Root cause: NO FAILURE NON CORE
Sources checked:
UniProtKB:Q920R0 · mouse Als2 SUPPORTS TRANSFER
Mouse Als2 is the ortholog source. PMID:17093100 provides mouse GRIP1/AMPA and postsynaptic localization evidence; retain species-specific limits on transfer to human.
ensembl:ENSMUSP00000027178 UNRESOLVED
The machine assertion supplies this mouse Ensembl protein alongside Q920R0; the exact historical peptide version and donor annotation were not separately recovered.
GO:0016197 endosomal transport
IBA
GO_REF:0000033
ACCEPT
Summary: ALS2 performs nucleotide exchange that supports endosomal membrane transport.
Reason: The IBA represents inheritance from PTN002338289 with fly and mouse descendants. The precise PAINT placement was not recovered. Direct Rab5 exchange and human-cDNA macropinosome-to-transferrin-positive-endosome fusion in PMID:17409386 substantiate participation in endosomal transport, independently of motor-neuron loss phenotypes. No evidence of target-specific loss opposes the ancestral inference.
Propagation Review
Root cause: NO FAILURE CORE
Sources checked:
FB:FBgn0037116 · Drosophila Als2 UNRESOLVED
Official FlyBase/NCBI identify Drosophila Als2/CG7158. The exact historical experimental row seeding this PAINT node was not reconstructed; target Rab5/endosomal evidence independently corroborates the broad function.
MGI:MGI:1921268 · mouse Als2 UNRESOLVED
Official MGI/MouseMine identify mouse Als2. Mouse-neuron evidence is distinguished from human constructs expressed in rodent cells. Historical PAINT source-row/node placement was not independently reconstructed.
PANTHER:PTN002338289 UNRESOLVED
This is the PAINT ancestral node, not a donor count. Its exact tree/MSA and IBD placement were not recovered; direct target evidence supports the term without establishing or contradicting the historical node placement.
Supporting Evidence:
PMID:15247254
This homo-oligomerization is crucial for the Rab5GEF activity in vitro and the ALS2-mediated endosome enlargement in the cells.
PMID:17409386
At later endocytic stages macropinosomal ALS2 augments fusion of the ALS2-localized macropinosomes with the transferrin-positive endosomes, depending on the ALS2-associated Rab5GEF activity.
GO:0030027 lamellipodium
IEA
GO_REF:0000107
ACCEPT
Summary: Alsin can localize to lamellipodia and related actin-rich protrusions.
Reason: The mouse Als2 source is compatible with conserved localization. PMID:15033976 independently expresses human ALS2 derived from human neuronal cDNA/KIAA1563 in mouse NIH3T3 cells and localizes the tagged protein to peripheral actin-rich protrusions. Endogenous NIH3T3 staining is mouse, and rat hippocampal localization is separate; neither is mislabeled as endogenous human evidence. ALS2 recruitment, rather than autonomous induction of lamellipodia, is the supported claim.
Propagation Review
Root cause: NO FAILURE CORE
Sources checked:
UniProtKB:Q920R0 · mouse Als2 SUPPORTS TRANSFER
Mouse Als2 is the ortholog source. Independent human ALS2 constructs/endogenous-cell observations corroborate the relevant location; this does not reconstruct every original mouse source row.
ensembl:ENSMUSP00000027178 UNRESOLVED
The machine assertion supplies this mouse Ensembl protein alongside Q920R0; the exact historical peptide version and donor annotation were not separately recovered.
Supporting Evidence:
PMID:15033976
We also found that alsin was present in membrane ruffles and lamellipodia.
GO:0030027 lamellipodium
ISS
GO_REF:0000024
ACCEPT
Summary: Lamellipodial localization is supported by ortholog and human-construct evidence.
Reason: The mouse Als2 source is compatible with conserved localization. PMID:15033976 independently expresses human ALS2 derived from human neuronal cDNA/KIAA1563 in mouse NIH3T3 cells and localizes the tagged protein to peripheral actin-rich protrusions. Endogenous NIH3T3 staining is mouse, and rat hippocampal localization is separate; neither is mislabeled as endogenous human evidence. ALS2 recruitment, rather than autonomous induction of lamellipodia, is the supported claim.
Propagation Review
Root cause: NO FAILURE CORE
Sources checked:
UniProtKB:Q920R0 · mouse Als2 SUPPORTS TRANSFER
Mouse Als2 is the ortholog source. Independent human ALS2 constructs/endogenous-cell observations corroborate the relevant location; this does not reconstruct every original mouse source row.
Supporting Evidence:
PMID:15033976
We also found that alsin was present in membrane ruffles and lamellipodia.
GO:0030425 dendrite
IBA
GO_REF:0000033
ACCEPT
Summary: Dendritic alsin localization is consistent with its neuronal endosomal role.
Reason: PTN002918520 is the ancestral source; extant evidence includes mouse Als2, rat Als2 and human ALS2. The human target in WITH/FROM is expected experimental grounding. The antibody-defined human spinal-cord somatodendritic finding in PMID:15371724 supports the location, together with cultured-neuron trafficking studies. Exact node placement is unresolved, not disproved.
Propagation Review
Root cause: NO FAILURE CORE
Sources checked:
MGI:MGI:1921268 · mouse Als2 UNRESOLVED
Official MGI/MouseMine identify mouse Als2. Mouse-neuron evidence is distinguished from human constructs expressed in rodent cells. Historical PAINT source-row/node placement was not independently reconstructed.
PANTHER:PTN002918520 UNRESOLVED
This is the PAINT ancestral node, not a donor count. Its exact tree/MSA and IBD placement were not recovered; direct target evidence supports the term without establishing or contradicting the historical node placement.
RGD:1310372 · rat Als2 SUPPORTS TRANSFER
Official NCBI Gene363235 identifies rat Als2 and the RGD identifier. Rodent neuronal localization in PMID:15371724/16049005 supports the relevant compartment, while human somatodendritic localization independently supports the target.
UniProtKB:Q96Q42 · human ALS2 SUPPORTS TRANSFER
The target is a legitimate extant experimental source. Rab5 exchange/binding and human localization papers support the relevant target function; self-inclusion in PAINT is not circular.
Supporting Evidence:
PMID:15371724
ARDA was also selectively localized to the somatodendritic compartment of motor neurons in human spinal cord.
GO:0030425 dendrite
IDA
PMID:15371724
A novel somatodendritic marker defined by a peptide derived ...
ACCEPT
Summary: An ALS2-derived antibody marks the human somatodendritic compartment.
Reason: PMID:15371724 explicitly reports ARDA staining in motor-neuron soma and dendrites of human spinal cord, as well as rodent cultures and sections. Accept the positive human location while acknowledging that the full antigen-specificity controls were not inspected. Its rat-neuron nuclear/axonal negatives should not be promoted to universal human NOT annotations.
Supporting Evidence:
PMID:15371724
ARDA was also selectively localized to the somatodendritic compartment of motor neurons in human spinal cord.
GO:0030425 dendrite
IEA
GO_REF:0000117
ACCEPT
Summary: The ARBA dendritic annotation has independent human localization support.
Reason: ARBA00028031 is the automated source; its full learned rule was not reconstructed. The human spinal-cord antibody localization in PMID:15371724 independently corroborates dendrites, so acceptance does not rely solely on the automated inference.
Propagation Review
Root cause: NO FAILURE CORE
Sources checked:
ARBA:ARBA00028031 UNRESOLVED
The exact learned rule and training-source chain were not reconstructed; independent human somatodendritic immunostaining supports the target location.
Supporting Evidence:
PMID:15371724
ARDA was also selectively localized to the somatodendritic compartment of motor neurons in human spinal cord.
GO:0030426 growth cone
ISS
GO_REF:0000024
KEEP AS NON CORE
Summary: Growth-cone localization is a neuronal, developmental context of alsin.
Reason: P0C5Y8 is rat Als2. Full PMID:16049005 locates endogenous protein with Rac in rat neuronal growth cones and tests human ALS2 in rat-neuron outgrowth assays. This is positive donor evidence compatible with mammalian conservation; it is not direct localization of endogenous human protein in adult motor-neuron growth cones. Retain this contextual subcellular specialization outside the compact general trafficking core.
Propagation Review
Root cause: NO FAILURE NON CORE
Sources checked:
UniProtKB:P0C5Y8 · rat Als2 SUPPORTS TRANSFER
Primary protein mapping identifies rat Als2. PMID:16049005 full Methods uses rat neuronal growth-cone localization; the human target location is inferred by conservation, not directly measured in that donor experiment.
Supporting Evidence:
PMID:16049005
Here we demonstrate that ALS2 is present within growth cones of neurons, in which it co-localizes with Rac.
GO:0031267 small GTPase binding
IBA
GO_REF:0000033
ACCEPT
Summary: Binding small GTPases is integral to alsin function.
Reason: The PAINT node PTN002338289 includes human ALS2 and mouse Als2cl/MGI2447532. The latter is an ALS2-related paralog whose original paper reports Rab5 binding, not evidence that all ALS2 functions transfer unchanged. Human ALS2 directly binds Rab5 in the original studies and active Rac1 in PMID:17409386. Exact node reconstruction remains unresolved; own-target evidence is legitimate and not circular.
Propagation Review
Root cause: NO FAILURE CORE
Sources checked:
MGI:MGI:2447532 · mouse Als2cl UNRESOLVED
Official MGI identifies Als2cl, an ALS2-related paralog. PMID:15388334 reports Rab5 binding and endosome effects for ALS2CL; its abstract includes human and mouse products but does not resolve every construct-specific assay. This is family evidence, not proof that all ALS2-specific roles are shared.
PANTHER:PTN002338289 UNRESOLVED
This is the PAINT ancestral node, not a donor count. Its exact tree/MSA and IBD placement were not recovered; direct target evidence supports the term without establishing or contradicting the historical node placement.
UniProtKB:Q96Q42 · human ALS2 SUPPORTS TRANSFER
The target is a legitimate extant experimental source. Rab5 exchange/binding and human localization papers support the relevant target function; self-inclusion in PAINT is not circular.
Supporting Evidence:
PMID:12837691
Here we show that the ALS2 protein specifically binds to small GTPase Rab5 and functions as a GEF for Rab5.
PMID:15388334
ALS2CL exhibited a specific but a relatively weak Rab5-GEF activity with accompanying rather strong Rab5-binding properties.
PMID:17409386
ALS2 preferentially interacts with activated Rac1.
GO:0031267 small GTPase binding
IDA
PMID:12837691
ALS2, a novel guanine nucleotide exchange factor for the sma...
ACCEPT
Summary: ALS2 binds Rab5 as its exchange substrate.
Reason: The source abstract directly states Rab5 binding. Full binding experiments in PMID:15247254 independently distinguish ALS2–Rab5 association from exchange competence. Keep the specific small-GTPase-binding MF without substituting a generic protein-binding term.
Supporting Evidence:
PMID:12837691
Here we show that the ALS2 protein specifically binds to small GTPase Rab5 and functions as a GEF for Rab5.
GO:0031267 small GTPase binding
IDA
PMID:15247254
Homo-oligomerization of ALS2 through its unique carboxyl-ter...
ACCEPT
Summary: ALS2 physically associates with Rab5A independently of full exchange competence.
Reason: Full PMID:15247254 Figure 5B tests affinity-isolated ALS2 fragments with Rab5A and identifies inactive constructs that still bind. Thus binding is a directly measured function and cannot be equated with catalytic exchange.
Supporting Evidence:
PMID:12837691
Here we show that the ALS2 protein specifically binds to small GTPase Rab5 and functions as a GEF for Rab5.
GO:0031267 small GTPase binding
NAS
PMID:16670179
The first ALS2 missense mutation associated with JPLS reveal...
ACCEPT
Summary: Small-GTPase binding is correct, with direct evidence from earlier mechanistic studies.
Reason: PMID:16670179 summarizes Rab5 binding in its background; its new experiments concern human G540E, localization and survival in SK-N-BE cells. Retain the NAS citation and the correct binding annotation, attaching independent primary binding support from PMID:12837691 and PMID:15247254 rather than attributing a new purified-binding assay to the clinical study.
Supporting Evidence:
PMID:12837691
Here we show that the ALS2 protein specifically binds to small GTPase Rab5 and functions as a GEF for Rab5.
GO:0031982 vesicle
IDA
PMID:12837691
ALS2, a novel guanine nucleotide exchange factor for the sma...
ACCEPT
Summary: The broad vesicular location is supported by endosomal association.
Reason: PMID:12837691 explicitly places ALS2 on Rab5/EEA1-positive endosomal compartments. Vesicle is an accurate broad CC at the source resolution; more specific early-endosome rows are retained separately. This does not imply association with every vesicle class. This is broader coverage of the same endosomal pool, not an additional compartment or independent experiment; no extra core location is added.
Supporting Evidence:
PMID:12837691
Ectopically expressed ALS2 protein localizes with Rab5 and early endosome antigen-1 (EEA1) onto early endosomal compartments and stimulates the enlargement of endosomes in cultured cortical neurons.
GO:0032991 protein-containing complex
IDA
PMID:15247254
Homo-oligomerization of ALS2 through its unique carboxyl-ter...
MODIFY
Summary: The functional ALS2 oligomer is a guanyl-nucleotide exchange factor complex.
Reason: Full PMID:15247254 reports self-association by Y2H/co-immunoprecipitation, a co-purifying oligomer, Rab5 GDP release and loss of exchange after disruption of oligomerization. Live GO:0032045 describes a protein complex that stimulates guanyl-nucleotide exchange and does not require heterologous subunits. Refine generic complex membership to that functional class without asserting a native octamer, a particular stoichiometry or ALS2CL membership.
Supporting Evidence:
PMID:15247254
ALS2 forms a homophilic oligomer through its distinct C-terminal regions.
PMID:15247254
This homo-oligomerization is crucial for the Rab5GEF activity in vitro and the ALS2-mediated endosome enlargement in the cells.
GO:0035022 positive regulation of Rac protein signal transduction
IC
PMID:16049005
ALS2/Alsin regulates Rac-PAK signaling and neurite outgrowth...
MARK AS OVER ANNOTATED
Summary: The contextual Rac-signaling result is supported, but the IC derivation is superseded by direct evidence.
Reason: Full PMID:16049005 measures increased GTP-bound Rac1 after human ALS2 expression in CHO cells, with DH-domain dependence. This supports a contextual positive signaling effect even though the original IC source GO:0043547 has a hydrolysis-specific definition and is separately refined to this same Rac-signaling term. Preserve that directly assayed result through the GO:0043547 IDA row's proposed replacement; the IC row adds no independent support once its premise is replaced. This is an IC-to-IDA evidence upgrade, not rejection of the cellular result. Retaining both as separate assertions would duplicate the claim and leave the IC inference without a distinct premise. PMID:17409386 instead finds preferential binding to active Rac1 and no Rac activation in its systems, so the positive response remains contextual rather than universal direct Rac-GEF chemistry.
Propagation Review
Root cause: SOURCE BAD
Sources checked:
GO:0043547 SOURCE BAD
The hydrolysis-specific IC premise does not describe the Rac-GTP occupancy assay and is being replaced by the conclusion term itself. The direct IDA refinement supersedes this inference; no circularity is alleged for the unmodified historical GOA record or for any PAINT source.
Supporting Evidence:
PMID:16049005
Furthermore, ALS2 stimulates Rac but not Rho or Cdc42 activities, and this induces a corresponding increase in PAK1 activity.
GO:0042802 identical protein binding
IDA
PMID:15247254
Homo-oligomerization of ALS2 through its unique carboxyl-ter...
ACCEPT
Summary: ALS2 self-association is functionally important for its exchange activity.
Reason: Y2H identifies ALS2 itself, and full co-immunoprecipitation and gel-filtration experiments corroborate physical self-association. Oligomerization-defective constructs lose Rab5 exchange. This is a specific functional assembly interaction, not an uninformative isolated binding hit.
Supporting Evidence:
PMID:15247254
A yeast two-hybrid screen for interacting proteins with the ALS2 C-terminal portion identified ALS2 itself.
PMID:15247254
This homo-oligomerization is crucial for the Rab5GEF activity in vitro and the ALS2-mediated endosome enlargement in the cells.
GO:0042803 protein homodimerization activity
IPI
PMID:15247254
Homo-oligomerization of ALS2 through its unique carboxyl-ter...
MODIFY
Summary: Self-binding is demonstrated; a fixed homodimer is not established by this source.
Reason: Full PMID:15247254 Figure 3 favors a larger oligomer rather than a dimer. Figure 7 offers alternative assembly models, one with dimeric building units and one without; Y2H/co-immunoprecipitation alone does not resolve the native subunit count. PMID:30224357 later revises the major WT assembly to a tetramer under its conditions. Generalize to identical protein binding, preserving demonstrated self-association without claiming dimers cannot occur. The replacement converges on the existing GO:0042802 annotation from the same paper; retain the supporting self-association evidence when consolidating that claim.
Proposed replacements: identical protein binding
Supporting Evidence:
PMID:15247254
ALS2 forms a homophilic oligomer through its distinct C-terminal regions.
PMID:30224357
Furthermore, most WT ALS2 complexes were tetramers.
GO:0043197 dendritic spine
IEA
GO_REF:0000107
KEEP AS NON CORE
Summary: Dendritic-spine localization is a specialized synaptic alsin pool.
Reason: The mouse Als2 transfer is supported by mouse-neuron distribution and GRIP1-related synaptic findings in PMID:17093100. It is reasonable to retain a conserved neuronal subcompartment while keeping model-specific localization distinct from direct human spine measurements and from the general endosomal exchange mechanism.
Propagation Review
Root cause: NO FAILURE NON CORE
Sources checked:
UniProtKB:Q920R0 · mouse Als2 SUPPORTS TRANSFER
Mouse Als2 is the ortholog source. PMID:17093100 provides mouse GRIP1/AMPA and postsynaptic localization evidence; retain species-specific limits on transfer to human.
ensembl:ENSMUSP00000027178 UNRESOLVED
The machine assertion supplies this mouse Ensembl protein alongside Q920R0; the exact historical peptide version and donor annotation were not separately recovered.
GO:0043539 protein serine/threonine kinase activator activity
IDA
PMID:16049005
ALS2/Alsin regulates Rac-PAK signaling and neurite outgrowth...
MARK AS OVER ANNOTATED
Summary: The downstream PAK1 response does not establish direct kinase-activator binding.
Reason: GO:0043539 requires binding a serine/threonine kinase and increasing its activity. PMID:16049005 measures a Rac-associated PAK1 response without demonstrating ALS2–PAK1 binding, so that direct molecular-function assignment exceeds the evidence. The positive kinase response remains captured by the existing GO:0045860 row from this paper; no replacement biological-process assertion is needed.
Supporting Evidence:
PMID:16049005
Furthermore, ALS2 stimulates Rac but not Rho or Cdc42 activities, and this induces a corresponding increase in PAK1 activity.
GO:0043547 positive regulation of GTPase activity
IDA
PMID:16049005
ALS2/Alsin regulates Rac-PAK signaling and neurite outgrowth...
MODIFY
Summary: The assay measures Rac signaling activation rather than accelerated GTP hydrolysis.
Reason: GO:0043547 positively regulates GTPase catalytic activity, whose reaction is GTP hydrolysis. PMID:16049005 instead captures GTP-bound Rac1 with the PAK binding domain after human ALS2 expression. Increased active-state occupancy is not a hydrolysis-rate measurement. Positive regulation of Rac protein signal transduction represents the measured cellular result, with its context-dependent interpretation retained. The replacement supersedes the existing GO:0035022 IC row, which is marked over-annotated because its GO:0043547 premise is being replaced. Consolidate into this directly supported IDA assertion as an IC-to-IDA evidence upgrade, without duplicate coverage.
Supporting Evidence:
PMID:16049005
Furthermore, ALS2 stimulates Rac but not Rho or Cdc42 activities, and this induces a corresponding increase in PAK1 activity.
GO:0045860 positive regulation of protein kinase activity
IDA
PMID:16049005
ALS2/Alsin regulates Rac-PAK signaling and neurite outgrowth...
KEEP AS NON CORE
Summary: Human ALS2 expression increases downstream PAK1 activity in the tested system.
Reason: Full PMID:16049005 measures kinase activity of immunoprecipitated PAK1 using myelin basic protein and radiolabeled ATP after human ALS2 expression in CHO cells. The response is DH-domain-dependent and accompanies increased Rac-GTP. This is a positive pathway effect, not ALS2 protein-kinase catalysis or proven direct ALS2–PAK binding; retain it as contextual signaling.
Supporting Evidence:
PMID:16049005
Furthermore, ALS2 stimulates Rac but not Rho or Cdc42 activities, and this induces a corresponding increase in PAK1 activity.
GO:0048812 neuron projection morphogenesis
IDA
PMID:16049005
ALS2/Alsin regulates Rac-PAK signaling and neurite outgrowth...
KEEP AS NON CORE
Summary: Human ALS2 promotes neurite extension in cultured rat neurons.
Reason: Full PMID:16049005 transfects human ALS2 into embryonic rat cortical/hippocampal cultures and measures neurite length, with dominant-negative Rac1 but not Rab5 blocking the effect. This is positive construct-level participation in a neuronal morphogenesis response, not merely disease necessity. Retain the contextual process rather than making it the universal biochemical core.
Supporting Evidence:
PMID:16049005
Finally, we demonstrate that ALS2 promotes neurite outgrowth.
GO:0051036 regulation of endosome size
IEP
PMID:15247254
Homo-oligomerization of ALS2 through its unique carboxyl-ter...
ACCEPT
Summary: ALS2 exchange and self-association regulate endosome size in the tested cells.
Reason: Full PMID:15247254 Figure 6 compares the constitutively active 695–1657 fragment with oligomerization- or GEF-defective variants in HeLa cells. EEA1-positive endosome enlargement depends on functional ALS2; the original IEP code is preserved. These engineered-fragment experiments support regulation, without implying that endogenous full-length ALS2 invariably causes giant endosomes.
Supporting Evidence:
PMID:15247254
This homo-oligomerization is crucial for the Rab5GEF activity in vitro and the ALS2-mediated endosome enlargement in the cells.
GO:0051260 protein homooligomerization
IDA
PMID:15247254
Homo-oligomerization of ALS2 through its unique carboxyl-ter...
ACCEPT
Summary: Functional homooligomer formation is integral to alsin activity.
Reason: ALS2 forms self-associated assemblies, and the source directly links disruption of the oligomerization region to loss of Rab5 exchange and endosomal effects. Preserve the broad homooligomerization process while distinguishing the source’s proposed octamer from the later tetramer-dominated measurements in PMID:30224357. No fixed native stoichiometry is required for this term.
Supporting Evidence:
PMID:15247254
ALS2 forms a homophilic oligomer through its distinct C-terminal regions.
PMID:15247254
This homo-oligomerization is crucial for the Rab5GEF activity in vitro and the ALS2-mediated endosome enlargement in the cells.
PMID:30224357
The ALS2 gene product, ALS2/alsin, forms a homophilic oligomer and acts as a guanine nucleotide-exchange factor (GEF) for the small GTPase Rab5. This oligomerization is crucial for both Rab5 activation and ALS2-mediated endosome fusion and maturation in cells.
PMID:30224357
Furthermore, most WT ALS2 complexes were tetramers.
GO:0098978 glutamatergic synapse
IEA
GO_REF:0000107
KEEP AS NON CORE
Summary: Glutamatergic synapses provide a neuronal context for alsin-mediated trafficking.
Reason: The transfer is from mouse Als2. PMID:17093100 combines mouse-neuron/brain distribution, GRIP1 association and AMPA-receptor surface/physiological measurements. These support a synaptic context beyond a nonspecific survival phenotype, with human conservation inferred rather than directly measured. Retain as non-core and do not add a new neurotransmission MF.
Propagation Review
Root cause: NO FAILURE NON CORE
Sources checked:
UniProtKB:Q920R0 · mouse Als2 SUPPORTS TRANSFER
Mouse Als2 is the ortholog source. PMID:17093100 provides mouse GRIP1/AMPA and postsynaptic localization evidence; retain species-specific limits on transfer to human.
ensembl:ENSMUSP00000027178 UNRESOLVED
The machine assertion supplies this mouse Ensembl protein alongside Q920R0; the exact historical peptide version and donor annotation were not separately recovered.
Supporting Evidence:
PMID:17093100
the subcellular distribution of GRIP1 was altered in ALS2(-/-) spinal motor neurons, which correlates with a significant reduction of AMPA-type glutamate receptor subunit 2 (GluR2) at the synaptic/cell surface of ALS2(-/-) neurons.
GO:0099072 regulation of postsynaptic membrane neurotransmitter receptor levels
IEA
GO_REF:0000107
KEEP AS NON CORE
Summary: Alsin contributes to receptor trafficking in the tested postsynaptic context.
Reason: Mouse PMID:17093100 reports an ALS2–GRIP1 association, altered dendritic GRIP1 distribution, altered synaptic receptor physiology and reduced surface GluR2 after AMPA challenge in Als2-deficient neurons. This connects a trafficking/scaffold role to receptor levels more specifically than knockout necessity alone. The existing ortholog transfer is biologically plausible, but its native human implementation and exact molecular coupling remain unmeasured in that source; retain the contextual process without adding it to the general Rab5 core.
Propagation Review
Root cause: NO FAILURE NON CORE
Sources checked:
UniProtKB:Q920R0 · mouse Als2 SUPPORTS TRANSFER
Mouse Als2 is the ortholog source. PMID:17093100 provides mouse GRIP1/AMPA and postsynaptic localization evidence; retain species-specific limits on transfer to human.
ensembl:ENSMUSP00000027178 UNRESOLVED
The machine assertion supplies this mouse Ensembl protein alongside Q920R0; the exact historical peptide version and donor annotation were not separately recovered.
Supporting Evidence:
PMID:17093100
Here, we report that alsin interacted with glutamate receptor interacting protein 1 (GRIP1) both in vitro and in vivo, and colocalized with GRIP1 in neurons.
PMID:17093100
the subcellular distribution of GRIP1 was altered in ALS2(-/-) spinal motor neurons, which correlates with a significant reduction of AMPA-type glutamate receptor subunit 2 (GluR2) at the synaptic/cell surface of ALS2(-/-) neurons.

Core Functions

The long alsin protein forms a functional self-associated Rab5 exchange factor. Its VPS9-containing C-terminal region promotes GDP release from Rab5, and regulated recruitment from the cytosol to early endosomal membranes couples this exchange to endosome fusion and membrane transport. Oligomerization supports activity; the core does not require a fixed native subunit count or direct Rac1 exchange catalysis.

Supporting Evidence:
  • PMID:12837691
    Here we show that the ALS2 protein specifically binds to small GTPase Rab5 and functions as a GEF for Rab5.
  • PMID:15247254
    This homo-oligomerization is crucial for the Rab5GEF activity in vitro and the ALS2-mediated endosome enlargement in the cells.
  • PMID:12837691
    Further, the DH/PH domain in the middle portion of ALS2 protein enhances the VPS9 domain-mediated endosome fusions.
  • PMID:15033976
    We found that the Vps9p domain of alsin has Rab5 guanine nucleotide exchange activity.
  • PMID:17409386
    At later endocytic stages macropinosomal ALS2 augments fusion of the ALS2-localized macropinosomes with the transferrin-positive endosomes, depending on the ALS2-associated Rab5GEF activity.
  • PMID:30224357
    The ALS2 gene product, ALS2/alsin, forms a homophilic oligomer and acts as a guanine nucleotide-exchange factor (GEF) for the small GTPase Rab5. This oligomerization is crucial for both Rab5 activation and ALS2-mediated endosome fusion and maturation in cells.

References

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Suggested Questions for Experts

Q: Which original PMID:12837691 experiment supports the nuclear and lysosomal-transport assertions, and was GTP hydrolysis tested separately from nucleotide exchange?

Q: Can direct Rac1 GDP-release measurements reconcile positive cellular Rac–PAK responses with the human ALS2 active-Rac1-effector results?

Q: What are the native full-length ALS2 oligomeric states in human neurons, and which functions are retained by each alternatively spliced product?

Q: Can the individual ALS2–NEK1 Bioplex interaction and exact PTN002338289/PTN002918520 IBD placements be retrieved to complete source-specific verification?

Q: Does GO:0032045 appropriately cover the functional ALS2 homooligomer, whose subunits jointly support Rab5 exchange, or would a more explicit homomeric-complex term improve curation?

📚 Additional Documentation

Notes

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