AVEN

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0010972 negative regulation of G2/M transition of mitotic cell cycle	IBA GO_REF:0000033	KEEP AS NON CORE	Summary: AVEN participates in the DNA damage response and promotes G2/M checkpoint arrest. ATM phosphorylates AVEN at Ser135 and Ser138 upon DNA damage, and these phosphorylation sites are required for AVEN-driven checkpoint function. This IBA annotation is phylogenetically inferred and is consistent with experimental evidence showing AVEN's role in DNA damage checkpoint signaling. Reason: While AVEN does contribute to G2/M checkpoint arrest via ATM-dependent phosphorylation, this represents a secondary/modulatory function rather than AVEN's core anti-apoptotic role. The primary function of AVEN is inhibition of apoptosome assembly and BCL-xL stabilization. The checkpoint function is mechanistically distinct and should be retained as a non-core annotation. Supporting Evidence: file:human/AVEN/AVEN-deep-research-falcon.md ATM phosphorylates Aven at Ser135 and Ser138, and these sites are required for Aven-driven checkpoint function
GO:0006915 apoptotic process	IEA GO_REF:0000043	MODIFY	Summary: This IEA annotation is based on the UniProt keyword 'Apoptosis'. AVEN is indeed involved in apoptosis, but as a negative regulator. The term 'apoptotic process' is too general and does not capture AVEN's specific anti-apoptotic function. AVEN inhibits the intrinsic apoptosis pathway by binding Apaf-1 and preventing apoptosome assembly, and by stabilizing BCL-xL. Reason: The annotation is not wrong (AVEN is involved in the apoptotic process), but it lacks specificity. AVEN specifically negatively regulates apoptosis through direct inhibition of apoptosome assembly and BCL-xL stabilization. A more informative annotation would be 'negative regulation of apoptotic process' (GO:0043066), which is already annotated with IDA evidence. Proposed replacements: negative regulation of apoptotic process Supporting Evidence: PMID:10949025 Aven interferes with the ability of Apaf-1 to self-associate, suggesting that Aven impairs Apaf-1-mediated activation of caspases. Consistent with this idea, Aven inhibited the proteolytic activation of caspases in a cell-free extract and suppressed apoptosis induced by Apaf-1 plus caspase-9.
GO:0012505 endomembrane system	IEA GO_REF:0000044	ACCEPT	Summary: This IEA annotation is based on UniProt subcellular location mapping. UniProt states AVEN is "Associated with intracellular membranes" and is a peripheral membrane protein of the endomembrane system. The original Chau et al. 2000 paper showed AVEN localizes to light membrane/vesicular fractions with diffuse nuclear and reticular cytoplasmic staining. Later work showed AVEN co-localizes with cathepsin D in vesicular compartments. Reason: The annotation is consistent with experimental evidence showing AVEN association with intracellular membranes and vesicular compartments. This localization is functionally relevant as cathepsin D processing of AVEN in vesicular compartments releases its anti-apoptotic potential. Supporting Evidence: PMID:10949025 Aven, a novel inhibitor of caspase activation, binds Bcl-xL and Apaf-1 file:human/AVEN/AVEN-deep-research-falcon.md Aven localizes mainly to light membrane/vesicular fractions, with diffuse nuclear and reticular cytoplasmic staining; it can co-localize with cathepsin D (CathD) in vesicular compartments
GO:0005515 protein binding	IPI PMID:10949025 Aven, a novel inhibitor of caspase activation, binds Bcl-xL ...	REMOVE	Summary: This annotation reflects AVEN's binding to APAF1 (O14727) and BCL2L1/BCL-xL (Q07817). While the interactions are well-documented (AVEN was discovered through yeast two-hybrid screen for BCL-xL interactors), the term 'protein binding' is uninformative. More specific molecular function terms should be used. Reason: The term 'protein binding' (GO:0005515) is too generic to be informative. AVEN has specific, characterized binding partners (Apaf-1 and BCL-xL) with defined functional consequences. The binding to Apaf-1 inhibits apoptosome assembly, while BCL-xL binding stabilizes and potentiates this anti-apoptotic protein. More specific terms like 'BH domain binding' (GO:0051400) for BCL-xL interaction would be more appropriate, though the core function is better captured by process annotations. Supporting Evidence: PMID:10949025 Aven is broadly expressed and is conserved in other mammalian species. Only those mutants of Bcl-x(L)that retain their antiapoptotic activity are capable of binding Aven.
GO:0005829 cytosol	TAS Reactome:R-HSA-6805507	ACCEPT	Summary: This TAS annotation from Reactome reflects AVEN localization in the cytosol where it can interact with Apaf-1 to inhibit apoptosome assembly. Apoptosome formation occurs in the cytosol following cytochrome c release from mitochondria, so cytosolic localization of AVEN is required for its anti-apoptotic function. Reason: Cytosolic localization is consistent with AVEN's function as an inhibitor of apoptosome assembly. The Reactome pathway 'APAF1 binds AVEN' documents this interaction in the cytosol. AVEN also associates with membrane fractions, but cytosolic AVEN is the pool that interacts with Apaf-1 to prevent caspase activation. Supporting Evidence: Reactome:R-HSA-6805507 The binding of AVEN to apoptotic protease activating factor 1 (APAF1) is thought to interfere with the ability of APAF1 to self-associate during apoptosome assembly
GO:0016020 membrane	IDA PMID:10949025 Aven, a novel inhibitor of caspase activation, binds Bcl-xL ...	ACCEPT	Summary: This IDA annotation indicates AVEN associates with membranes. The original Chau et al. paper showed AVEN localizes to light membrane fractions by subcellular fractionation. UniProt describes AVEN as a peripheral membrane protein of the endomembrane system. Reason: The membrane localization is experimentally validated and functionally relevant. AVEN co-localizes with cathepsin D in vesicular/membrane compartments where proteolytic processing removes the N-terminal inhibitory domain to unleash AVEN's full anti-apoptotic activity. Both cytosolic and membrane-associated pools of AVEN are physiologically relevant. Supporting Evidence: PMID:10949025 Aven, a novel inhibitor of caspase activation, binds Bcl-xL and Apaf-1 file:human/AVEN/AVEN-deep-research-falcon.md Biochemical fractionation and microscopy place Aven in light membrane/vesicular pools and nucleus/cytoplasm
GO:0043066 negative regulation of apoptotic process	IDA PMID:10949025 Aven, a novel inhibitor of caspase activation, binds Bcl-xL ...	ACCEPT	Summary: This is the core functional annotation for AVEN. AVEN negatively regulates apoptosis through two mechanisms: (1) binding Apaf-1 and interfering with its self-association, thereby blocking apoptosome assembly and caspase-9 activation; (2) binding and stabilizing BCL-xL to potentiate its anti-apoptotic function. Chau et al. demonstrated that AVEN inhibited caspase proteolytic activation in cell-free extracts and suppressed apoptosis induced by Apaf-1 plus caspase-9. AVEN also protected against death in a mouse Sindbis virus infection model. Reason: This annotation accurately captures AVEN's core function as an anti-apoptotic regulator. The IDA evidence from the original discovery paper is strong, demonstrating both biochemical inhibition of caspase activation and cellular protection from apoptosis. This is a legitimate, evolved anti-apoptotic function, not a downstream metabolic effect. Supporting Evidence: PMID:10949025 Aven interferes with the ability of Apaf-1 to self-associate, suggesting that Aven impairs Apaf-1-mediated activation of caspases. Consistent with this idea, Aven inhibited the proteolytic activation of caspases in a cell-free extract and suppressed apoptosis induced by Apaf-1 plus caspase-9.
GO:1905101 negative regulation of apoptosome assembly	IDA PMID:10949025 Aven, a novel inhibitor of caspase activation, binds Bcl-xL ...	NEW	Summary: AVEN directly inhibits apoptosome assembly by binding Apaf-1 and preventing its self-association. This is the specific mechanistic step at which AVEN acts to inhibit apoptosis. Reason: This term (GO:1905101) more precisely describes AVEN's mechanism of action than the broader 'negative regulation of apoptotic process'. AVEN binds Apaf-1 and interferes with its oligomerization, which is required for apoptosome formation. This is the proximal step that AVEN inhibits to block caspase activation. Supporting Evidence: PMID:10949025 Aven interferes with the ability of Apaf-1 to self-associate, suggesting that Aven impairs Apaf-1-mediated activation of caspases. Reactome:R-HSA-6805507 The binding of AVEN to apoptotic protease activating factor 1 (APAF1) is thought to interfere with the ability of APAF1 to self-associate during apoptosome assembly
GO:0051400 BH domain binding	IDA PMID:10949025 Aven, a novel inhibitor of caspase activation, binds Bcl-xL ...	NEW	Summary: AVEN binds BCL-xL (BCL2L1), an anti-apoptotic BCL-2 family member. AVEN was originally identified by yeast two-hybrid screen for BCL-xL interactors. Computational analysis has identified a predicted BH3-like motif in AVEN (aa 141-153) that may mediate this interaction. Only BCL-xL mutants that retain anti-apoptotic activity can bind AVEN. Reason: This molecular function annotation would capture AVEN's specific interaction with BCL-xL through the BH domain binding interface. This is more informative than generic 'protein binding' and reflects the BH3-like motif in AVEN that mediates the interaction. Supporting Evidence: PMID:10949025 Only those mutants of Bcl-x(L)that retain their antiapoptotic activity are capable of binding Aven. file:human/AVEN/AVEN-deep-research-falcon.md Computational/biophysical analyses identified a BH3-like segment in Aven (aa 141-153) predicted to bind BCL-xL with appreciable affinity