DAP1 (Death-associated protein 1) is a small (~15 kDa, 102 amino acids) intrinsically disordered, proline-rich cytoplasmic protein that functions primarily as a negative regulator of autophagy. DAP1 is a direct substrate of mTORC1. Under nutrient-rich conditions, mTOR phosphorylates DAP1 at Ser3 and Ser51, keeping it inactive. During starvation or mTOR inhibition, DAP1 is rapidly dephosphorylated and becomes functionally active to suppress autophagy, acting as a "brake" to prevent overactivation of autophagic flux (PMID:20537536). DAP1 was originally identified as a mediator of IFN-gamma-induced programmed cell death (PMID:7828849). Recent studies also implicate DAP1 in ribosome hibernation through association with ribosomes and interaction with eIF5A, preventing mRNA translation, which is particularly important in oocyte maturation (UniProt ISS evidence from zebrafish ortholog).
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0043022 ribosome binding | IBA GO_REF:0000033 | ACCEPT | Summary: DAP1 has been annotated with ribosome binding based on phylogenetic inference (IBA). This annotation is supported by UniProt functional annotation stating that DAP1 is a "Ribosome-binding protein involved in ribosome hibernation" with evidence from the zebrafish ortholog (UniProtKB:Q9I9N1). The protein associates with ribosomes and inhibits translation through its interaction with eIF5A at the polypeptide exit tunnel. Reason: The IBA annotation is well-supported by sequence similarity evidence from the zebrafish ortholog and is consistent with DAP1's described role in ribosome hibernation. UniProt explicitly states "Associates with ribosomes; inhibiting translation" and "Interacts with eiF5a (EIF5A and EIF5A2); inhibiting translation" (ECO:0000250|UniProtKB:Q9I9N1). While direct experimental evidence in human is limited, the phylogenetic conservation of this function across vertebrates supports this annotation. Supporting Evidence: UniProtKB:P51397 Associates with ribosomes; inhibiting translation (By similarity). Interacts with eiF5a (EIF5A and EIF5A2); inhibiting translation (By similarity). {ECO:0000250|UniProtKB:Q9I9N1}. file:human/DAP/DAP-deep-research-falcon.md DAP1 is a small (~15 kDa), proline-rich phosphoprotein... Molecular identity and structure: DAP1 is a 102-amino acid, proline-rich cytoplasmic protein that behaves as an intrinsically disordered protein (IDP). |
| GO:0141014 ribosome hibernation | IBA GO_REF:0000033 | ACCEPT | Summary: DAP1 is annotated with ribosome hibernation based on phylogenetic inference. UniProt describes DAP1 as a "Ribosome-binding protein involved in ribosome hibernation, a process during which ribosomes are stabilized in an inactive state and preserved from proteasomal degradation." The protein acts via association with eIF5A at the polypeptide exit tunnel, preventing mRNA translation. This function is particularly important in oocytes where ribosomes are stored and translationally repressed. Reason: This annotation correctly captures a key cellular process function of DAP1. UniProt explicitly describes DAP1's role: "Involved in ribosome hibernation in the mature oocyte by preventing mRNA translation, leading to ribosome inactivation (By similarity). Ribosomes, which are produced in large quantities during oogenesis, are stored and translationally repressed in the oocyte and early embryo (By similarity)" (ECO:0000250|UniProtKB:Q9I9N1). The IBA evidence from phylogenetic trees is appropriate for this conserved function. Supporting Evidence: UniProtKB:P51397 Ribosome-binding protein involved in ribosome hibernation, a process during which ribosomes are stabilized in an inactive state and preserved from proteasomal degradation (By similarity). Acts via its association with eiF5a (EIF5A and EIF5A2) at the polypeptide exit tunnel of the ribosome, preventing mRNA translation (By similarity). file:human/DAP/DAP-deep-research-falcon.md Subcellular context: Cytoplasmic localization aligns with its engagement with core autophagy machinery... with recent osteoblast data pinpointing an ATG16L1-LC3 functional axis |
| GO:0010507 negative regulation of autophagy | IBA GO_REF:0000033 | ACCEPT | Summary: DAP1 is a well-established negative regulator of autophagy, functioning as a direct mTORC1 substrate. The seminal work by Koren et al. (PMID:20537536) demonstrated that DAP1 knockdown enhanced autophagic flux, and that mTOR-dependent phosphorylation at Ser3 and Ser51 keeps DAP1 inactive under nutrient-rich conditions. During starvation, DAP1 dephosphorylation activates its autophagy-suppressive function, acting as a "brake" to prevent overactivation of autophagy. Reason: This is a core function of DAP1 with strong experimental support. The IBA annotation is consistent with direct experimental evidence (IMP) from PMID:20537536 which demonstrated that "knockdown enhanced autophagic flux" and showed the mechanism of mTOR-dependent regulation. This represents the "Gas and Brake" model where DAP1 counterbalances autophagic flux during nutrient deprivation. Supporting Evidence: PMID:20537536 Here we identify death-associated protein 1 (DAP1) as a novel substrate of mTOR that negatively regulates autophagy. The link of DAP1 to autophagy was first apparent in that its knockdown enhanced autophagic flux and in that it displayed a rapid decline in its phosphorylation in response to amino acid starvation. file:human/DAP/DAP-deep-research-falcon.md Core biochemical function: DAP1 is a negative regulator of autophagy and a direct substrate of mTORC1. Under nutrient-rich conditions, mTOR-dependent phosphorylation of DAP1 keeps it inactive; during starvation or mTOR inhibition, DAP1 is dephosphorylated and becomes functionally active to suppress autophagy |
| GO:0097190 apoptotic signaling pathway | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: DAP1 was originally identified as a mediator of IFN-gamma-induced programmed cell death (PMID:7828849). The original discovery used antisense RNA-mediated inactivation to show that DAP1 expression was "indispensable for the execution of this type of cell death." However, the precise molecular mechanism by which DAP1 participates in apoptotic signaling remains incompletely defined. Reason: While DAP1's involvement in cell death was the basis for its original identification and naming, subsequent research has established that its primary molecular function is autophagy regulation. The apoptotic function may be secondary to or downstream of its autophagy-regulatory role, given the known crosstalk between autophagy and apoptosis. The original 1995 study used functional cloning but did not elucidate the precise mechanism. This annotation should be retained but marked as non-core since the autophagy regulation function is better characterized and more central to DAP1's molecular identity. Supporting Evidence: PMID:7828849 In this system we have identified two novel genes whose expression was indispensable for the execution of this type of cell death... One of those genes (DAP-1) is expressed as a single 2.4-kb mRNA that codes for a basic, proline-rich, 15-kD protein. file:human/DAP/DAP-deep-research-falcon.md Identified DAP-1 as a small (~15 kDa), proline-rich phospho-protein implicated in IFN-gamma-induced programmed cell death; original functional cloning/identification of DAP1. |
| GO:0006417 regulation of translation | IEA GO_REF:0000043 | ACCEPT | Summary: This IEA annotation is derived from UniProt keyword mapping. DAP1 regulates translation through its ribosome-binding activity and association with eIF5A at the ribosome exit tunnel. This function is related to its role in ribosome hibernation, where it prevents mRNA translation and keeps ribosomes in an inactive, protected state. Reason: The annotation is consistent with DAP1's described molecular function. UniProt indicates DAP1 "Acts via its association with eiF5a (EIF5A and EIF5A2) at the polypeptide exit tunnel of the ribosome, preventing mRNA translation." While this is an IEA annotation, it is appropriately general and captures the translation regulatory aspect of DAP1's ribosome-associated function. The more specific GO:0141014 (ribosome hibernation) provides the mechanistic detail, but this broader term is also accurate. Supporting Evidence: UniProtKB:P51397 Acts via its association with eiF5a (EIF5A and EIF5A2) at the polypeptide exit tunnel of the ribosome, preventing mRNA translation (By similarity). file:human/DAP/DAP-deep-research-falcon.md Structural/biophysical perspective: The IDP nature of DAP1 suggests regulation via short linear motifs and post-translational modifications rather than stable domain-domain interfaces, aligning with its rapid phosphorylation/dephosphorylation behavior |
| GO:0006914 autophagy | IEA GO_REF:0000043 | ACCEPT | Summary: This IEA annotation from UniProt keyword mapping indicates involvement in autophagy. DAP1 is indeed involved in autophagy, specifically as a negative regulator. However, the parent term "autophagy" does not capture the directionality of DAP1's effect. Reason: While the more specific term GO:0010507 (negative regulation of autophagy) better captures DAP1's function, this broader IEA annotation is not incorrect. DAP1 is clearly involved in the autophagy process, acting to suppress it. The IEA mapping from the Autophagy keyword is appropriate at this level of specificity. The more precise experimental annotations (IMP for negative regulation of autophagy) provide the necessary detail about the direction of regulation. Supporting Evidence: PMID:20537536 DAP1, a novel substrate of mTOR, negatively regulates autophagy. file:human/DAP/DAP-deep-research-falcon.md Core biochemical function: DAP1 is a negative regulator of autophagy and a direct substrate of mTORC1. |
| GO:0006915 apoptotic process | IEA GO_REF:0000043 | KEEP AS NON CORE | Summary: This IEA annotation from UniProt keyword mapping indicates involvement in apoptosis. DAP1 was originally identified as a mediator of IFN-gamma-induced cell death, and UniProt includes "Apoptosis" as a keyword for this protein. Reason: The annotation reflects DAP1's historical identification as a death-associated protein involved in IFN-gamma-induced cell death. However, the primary molecular function of DAP1 is now understood to be autophagy regulation. The apoptotic involvement may be secondary or represent crosstalk between autophagy and apoptosis pathways. This broader IEA annotation is consistent with but less specific than the IGI and IMP annotations for apoptotic processes from experimental evidence. Supporting Evidence: PMID:7828849 Altogether, it is suggested that these two novel genes are candidates for positive mediators of programmed cell death that is induced by IFN-gamma. file:human/DAP/DAP-deep-research-falcon.md Autophagy/apoptosis crosstalk context: DAP1's role in tuning the balance between autophagy and apoptosis was previously demonstrated in a toxin model, supporting that DAP1 levels/status influence stress responses |
| GO:0006915 apoptotic process | IGI PMID:7828849 Identification of a novel serine/threonine kinase and a nove... | KEEP AS NON CORE | Summary: This IGI (Inferred from Genetic Interaction) annotation is based on the original 1995 study that identified DAP1. The study used antisense RNA-mediated inactivation to show that reducing DAP1 expression protected cells from IFN-gamma-induced cell death, suggesting a positive role in promoting apoptosis. The genetic interaction evidence comes from the observation that antisense knockdown of DAP1 rescued cells from death. Reason: The IGI evidence is valid based on the experimental design in PMID:7828849. However, this function is now considered secondary to DAP1's role in autophagy regulation. The original study demonstrated functional involvement in cell death but did not establish the molecular mechanism. Given that autophagy and apoptosis are interconnected processes, DAP1's effect on cell death may be mediated through its autophagy regulatory function. Retain as non-core function. Supporting Evidence: PMID:7828849 The antisense RNA-mediated inactivation of the two novel genes protected the cells from the IFN-gamma-induced cell death but not from the cytostatic effects of the cytokine or from a necrotic type of cell death. file:human/DAP/DAP-deep-research-falcon.md Identified DAP-1 as a small (~15 kDa), proline-rich phospho-protein implicated in IFN-gamma-induced programmed cell death |
| GO:0010507 negative regulation of autophagy | IMP PMID:20537536 DAP1, a novel substrate of mTOR, negatively regulates autoph... | ACCEPT | Summary: This IMP annotation is based on the landmark study by Koren et al. (2010) that established DAP1 as a negative regulator of autophagy. The study demonstrated that DAP1 knockdown enhanced autophagic flux, DAP1 phosphorylation rapidly declined upon amino acid starvation, and mTOR directly phosphorylates DAP1 at Ser3 and Ser51 to keep it inactive. Dephosphorylated DAP1 becomes an active suppressor of autophagy, functioning as a "brake" mechanism. Reason: This is a core function of DAP1 with strong direct experimental evidence. The IMP annotation is well-supported by the referenced publication which used knockdown experiments, phosphorylation site mapping, and mutant analysis to establish DAP1 as a negative regulator of autophagy. This represents DAP1's primary characterized molecular function and should be retained as a core annotation. Supporting Evidence: PMID:20537536 Mapping of the phosphorylation sites and analysis of phosphorylation mutants indicated that DAP1 is functionally silenced in growing cells through mTOR-dependent phosphorylations on Ser3 and Ser51. Inactivation of mTOR during starvation caused a rapid reduction in these phosphorylation sites and converted the protein into an active suppressor of autophagy. file:human/DAP/DAP-deep-research-falcon.md Demonstrated DAP1 is a direct mTOR substrate; mapped phosphorylation at Ser3 and Ser51 (phospho-DAP1 inactive under nutrient-rich conditions); starvation or mTOR inhibition causes dephosphorylation and activation of DAP1 which negatively regulates autophagy. |
| GO:0097190 apoptotic signaling pathway | IMP PMID:7828849 Identification of a novel serine/threonine kinase and a nove... | KEEP AS NON CORE | Summary: This IMP annotation references the original 1995 study identifying DAP1. However, reviewing PMID:7828849, the evidence is more accurately described as genetic interaction (antisense knockdown protection from cell death) rather than a direct mutant phenotype. The study identified DAP1 through functional cloning using antisense libraries and showed that its inactivation protected cells from IFN-gamma-induced death. Reason: While the evidence code may be debatable (the original study used antisense knockdown which could be considered either IMP or IGI), the functional association with apoptotic signaling is supported. However, as with other apoptosis-related annotations, this represents a secondary or historical function. The primary molecular mechanism of DAP1 is now understood to be autophagy regulation via mTORC1-dependent phosphorylation. The apoptotic signaling involvement may be a downstream consequence of autophagy dysregulation or represent early-stage characterization before the autophagy function was discovered. Retain as non-core. Supporting Evidence: PMID:7828849 Here, we report that gamma interferon (IFN-gamma) induced in HeLa cells a type of cell death that had cytological characteristics of programmed cell death. In this system we have identified two novel genes whose expression was indispensable for the execution of this type of cell death. file:human/DAP/DAP-deep-research-falcon.md Identified DAP-1 as a small (~15 kDa), proline-rich phospho-protein implicated in IFN-gamma-induced programmed cell death; original functional cloning/identification of DAP1. |
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Download this section (compressed HTML)Q: What is the precise molecular mechanism by which dephosphorylated DAP1 suppresses autophagy? Does it directly interact with ATG proteins or act through intermediate effectors? While DAP1's role as an autophagy suppressor is well-established, the downstream molecular targets of active (dephosphorylated) DAP1 remain incompletely characterized. Recent work suggests involvement of the ATG16L1-LC3 axis but direct binding partners have not been fully defined.
Q: Is DAP1's ribosome hibernation function in human cells as significant as in zebrafish, and does it operate in cell types beyond oocytes? The ribosome hibernation function is primarily characterized from zebrafish studies and inferred by sequence similarity. Direct experimental evidence in human cells and non-oocyte contexts would strengthen these annotations.
Q: How does DAP1 contribute to the crosstalk between autophagy and apoptosis, and is its original identification as a cell death mediator a direct or indirect effect? The relationship between DAP1's autophagy-suppressive function and its role in IFN-gamma-induced cell death remains unclear.
Experiment: Co-immunoprecipitation and proximity ligation assays to identify direct binding partners of dephosphorylated DAP1 in the autophagy machinery. This would clarify the molecular mechanism of autophagy suppression and potentially justify more specific molecular function annotations.
Experiment: Ribosome profiling and eIF5A co-localization studies in human cell lines under various nutrient conditions. This would provide direct experimental evidence for human DAP1's ribosome hibernation function, currently supported only by similarity to zebrafish ortholog.
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