Aps1 (YLR170C; also YAP19) is the 156-residue sigma1 small subunit of the S. cerevisiae AP-1 clathrin adaptor complex, a heterotetramer with the gamma-adaptin Apl4, the beta1-adaptin Apl2 and the mu1-adaptin Apm1. Aps1 is also the shared sigma subunit of the AP-1R variant, in which Apm2 replaces Apm1. It has a longin-like clathrin adaptor small-chain fold and belongs to the adaptor complexes small subunit family (PANTHER PTHR11753, subfamily SF5 together with S. pombe Aps1). AP-1 is the only yeast AP complex that binds clathrin; it co-fractionates with clathrin-coated vesicles and acts at the late Golgi/early endosome, where it sorts specific membrane cargo. Its best-characterised cargo is chitin synthase Chs3, which it keeps in an intracellular TGN/early endosome recycling loop through a dileucine signal recognised by the gamma/sigma subunits; AP-1 also retains the syntaxin Tlg1, and AP-1R sorts the v-SNARE Snc1. Loss of Aps1 has no detectable phenotype in otherwise wild-type cells but worsens the growth and alpha-factor maturation defects of clathrin heavy chain mutants, showing that AP-1 contributes to a subset of clathrin functions at the Golgi without being required for clathrin coat function in general.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003674 molecular_function | ND GO_REF:0000015 | MODIFY | Summary: ND root-term annotation (no molecular function data at the time it was made). Reason: The ND placeholder is superseded. Aps1 is the sigma subunit of AP-1, a clathrin adaptor complex: only AP-1 among the yeast AP complexes binds clathrin, and the AP-1 gamma/sigma hemicomplex is the site that recognises dileucine sorting signals such as that of Chs3. The sigma subunit contributes to, rather than alone executes, the complex-level clathrin-cargo adaptor activity (GO:0035615), which is also present here as an InterPro IEA row. Note that the adaptor activity is established for the AP-1 complex in yeast; a dileucine-binding role for Aps1 specifically is inferred from the family and is not directly assayed in S. cerevisiae. Proposed replacements: clathrin-cargo adaptor activity Supporting Evidence: PMID:10564262 As assessed by in vitro binding assays and coimmunoprecipitation, only AP-1 interacts with clathrin. PMID:26658609 Because the dileucine-based motif of Chs3 binds the Ξ³/Ο subunits present in both AP-1 and AP-1R |
| GO:0005515 protein binding | IPI PMID:10564262 Adaptor complex-independent clathrin function in yeast. | REMOVE | Summary: IPI protein binding with APL2/P36000, beta1-adaptin (AP-1 subunit). Reason: Bare GO:0005515 protein binding is uninformative and is removed under the repository protein-binding policy; removal does not dispute the interaction. The partner (APL2/P36000, beta1-adaptin) is another subunit of the yeast AP-1 heterotetramer (APL2 beta1, APM1 mu1, APL4 gamma), so the interaction is the subunit assembly of AP-1 itself, which is already captured by the experimentally supported part_of GO:0030121 AP-1 adaptor complex annotation. No more informative molecular function follows from subunit-subunit binding alone. Supporting Evidence: PMID:10564262 Using coimmunoprecipitation, the subunit composition of two complexes, AP-1 and AP-2R, has been defined. |
| GO:0005515 protein binding | IPI PMID:10564262 Adaptor complex-independent clathrin function in yeast. | REMOVE | Summary: IPI protein binding with APM1/Q00776, mu1-adaptin (AP-1 subunit). Reason: Bare GO:0005515 protein binding is uninformative and is removed under the repository protein-binding policy; removal does not dispute the interaction. The partner (APM1/Q00776, mu1-adaptin) is another subunit of the yeast AP-1 heterotetramer (APL2 beta1, APM1 mu1, APL4 gamma), so the interaction is the subunit assembly of AP-1 itself, which is already captured by the experimentally supported part_of GO:0030121 AP-1 adaptor complex annotation. No more informative molecular function follows from subunit-subunit binding alone. Supporting Evidence: PMID:10564262 Using coimmunoprecipitation, the subunit composition of two complexes, AP-1 and AP-2R, has been defined. |
| GO:0005515 protein binding | IPI PMID:11805826 Functional organization of the yeast proteome by systematic ... | REMOVE | Summary: IPI protein binding with APL2/P36000, beta1-adaptin (AP-1 subunit). Reason: Bare GO:0005515 protein binding is uninformative and is removed under the repository protein-binding policy; removal does not dispute the interaction. The partner (APL2/P36000, beta1-adaptin) is another subunit of the yeast AP-1 heterotetramer (APL2 beta1, APM1 mu1, APL4 gamma), so the interaction is the subunit assembly of AP-1 itself, which is already captured by the experimentally supported part_of GO:0030121 AP-1 adaptor complex annotation. No more informative molecular function follows from subunit-subunit binding alone. Supporting Evidence: PMID:10564262 Using coimmunoprecipitation, the subunit composition of two complexes, AP-1 and AP-2R, has been defined. |
| GO:0005515 protein binding | IPI PMID:16429126 Proteome survey reveals modularity of the yeast cell machine... | REMOVE | Summary: IPI protein binding with APL2/P36000, beta1-adaptin (AP-1 subunit). Reason: Bare GO:0005515 protein binding is uninformative and is removed under the repository protein-binding policy; removal does not dispute the interaction. The partner (APL2/P36000, beta1-adaptin) is another subunit of the yeast AP-1 heterotetramer (APL2 beta1, APM1 mu1, APL4 gamma), so the interaction is the subunit assembly of AP-1 itself, which is already captured by the experimentally supported part_of GO:0030121 AP-1 adaptor complex annotation. No more informative molecular function follows from subunit-subunit binding alone. Supporting Evidence: PMID:10564262 Using coimmunoprecipitation, the subunit composition of two complexes, AP-1 and AP-2R, has been defined. |
| GO:0005515 protein binding | IPI PMID:16429126 Proteome survey reveals modularity of the yeast cell machine... | REMOVE | Summary: IPI protein binding with APM1/Q00776, mu1-adaptin (AP-1 subunit). Reason: Bare GO:0005515 protein binding is uninformative and is removed under the repository protein-binding policy; removal does not dispute the interaction. The partner (APM1/Q00776, mu1-adaptin) is another subunit of the yeast AP-1 heterotetramer (APL2 beta1, APM1 mu1, APL4 gamma), so the interaction is the subunit assembly of AP-1 itself, which is already captured by the experimentally supported part_of GO:0030121 AP-1 adaptor complex annotation. No more informative molecular function follows from subunit-subunit binding alone. Supporting Evidence: PMID:10564262 Using coimmunoprecipitation, the subunit composition of two complexes, AP-1 and AP-2R, has been defined. |
| GO:0005515 protein binding | IPI PMID:16429126 Proteome survey reveals modularity of the yeast cell machine... | REMOVE | Summary: IPI protein binding with APL4/Q12028, gamma-adaptin (AP-1 subunit). Reason: Bare GO:0005515 protein binding is uninformative and is removed under the repository protein-binding policy; removal does not dispute the interaction. The partner (APL4/Q12028, gamma-adaptin) is another subunit of the yeast AP-1 heterotetramer (APL2 beta1, APM1 mu1, APL4 gamma), so the interaction is the subunit assembly of AP-1 itself, which is already captured by the experimentally supported part_of GO:0030121 AP-1 adaptor complex annotation. No more informative molecular function follows from subunit-subunit binding alone. Supporting Evidence: PMID:10564262 Using coimmunoprecipitation, the subunit composition of two complexes, AP-1 and AP-2R, has been defined. |
| GO:0005515 protein binding | IPI PMID:18467557 An in vivo map of the yeast protein interactome. | REMOVE | Summary: IPI protein binding with APL4/Q12028, gamma-adaptin (AP-1 subunit). Reason: Bare GO:0005515 protein binding is uninformative and is removed under the repository protein-binding policy; removal does not dispute the interaction. The partner (APL4/Q12028, gamma-adaptin) is another subunit of the yeast AP-1 heterotetramer (APL2 beta1, APM1 mu1, APL4 gamma), so the interaction is the subunit assembly of AP-1 itself, which is already captured by the experimentally supported part_of GO:0030121 AP-1 adaptor complex annotation. No more informative molecular function follows from subunit-subunit binding alone. Supporting Evidence: PMID:10564262 Using coimmunoprecipitation, the subunit composition of two complexes, AP-1 and AP-2R, has been defined. |
| GO:0005515 protein binding | IPI PMID:37968396 The social and structural architecture of the yeast protein ... | REMOVE | Summary: IPI protein binding with APL2/P36000, beta1-adaptin (AP-1 subunit). Reason: Bare GO:0005515 protein binding is uninformative and is removed under the repository protein-binding policy; removal does not dispute the interaction. The partner (APL2/P36000, beta1-adaptin) is another subunit of the yeast AP-1 heterotetramer (APL2 beta1, APM1 mu1, APL4 gamma), so the interaction is the subunit assembly of AP-1 itself, which is already captured by the experimentally supported part_of GO:0030121 AP-1 adaptor complex annotation. No more informative molecular function follows from subunit-subunit binding alone. Supporting Evidence: PMID:10564262 Using coimmunoprecipitation, the subunit composition of two complexes, AP-1 and AP-2R, has been defined. |
| GO:0005515 protein binding | IPI PMID:37968396 The social and structural architecture of the yeast protein ... | REMOVE | Summary: IPI protein binding with APM1/Q00776, mu1-adaptin (AP-1 subunit). Reason: Bare GO:0005515 protein binding is uninformative and is removed under the repository protein-binding policy; removal does not dispute the interaction. The partner (APM1/Q00776, mu1-adaptin) is another subunit of the yeast AP-1 heterotetramer (APL2 beta1, APM1 mu1, APL4 gamma), so the interaction is the subunit assembly of AP-1 itself, which is already captured by the experimentally supported part_of GO:0030121 AP-1 adaptor complex annotation. No more informative molecular function follows from subunit-subunit binding alone. Supporting Evidence: PMID:10564262 Using coimmunoprecipitation, the subunit composition of two complexes, AP-1 and AP-2R, has been defined. |
| GO:0005515 protein binding | IPI PMID:37968396 The social and structural architecture of the yeast protein ... | REMOVE | Summary: IPI protein binding with APL4/Q12028, gamma-adaptin (AP-1 subunit). Reason: Bare GO:0005515 protein binding is uninformative and is removed under the repository protein-binding policy; removal does not dispute the interaction. The partner (APL4/Q12028, gamma-adaptin) is another subunit of the yeast AP-1 heterotetramer (APL2 beta1, APM1 mu1, APL4 gamma), so the interaction is the subunit assembly of AP-1 itself, which is already captured by the experimentally supported part_of GO:0030121 AP-1 adaptor complex annotation. No more informative molecular function follows from subunit-subunit binding alone. Supporting Evidence: PMID:10564262 Using coimmunoprecipitation, the subunit composition of two complexes, AP-1 and AP-2R, has been defined. |
| GO:0005634 nucleus | IEA GO_REF:0000044 | MARK AS OVER ANNOTATED | Summary: Nucleus, transferred (ISS, and its SubCell IEA mapping) from S. pombe Aps1/vas2 (Q9P7N2), whose nuclear and cytoplasmic localization comes only from the genome-wide ORFeome GFP screen. Reason: The only basis is a large-scale GFP-fusion localization in fission yeast (PMID:16823372); the pombe AP-1 study that defined Golgi/endosome localization does not report a nuclear pool, and no S. cerevisiae data place Aps1 or any AP-1 subunit in the nucleus. A diffuse nucleocytoplasmic signal of an over-expressed small fusion is a common screen artefact. AP-1 has no known nuclear function, so the term over-states the evidence. Supporting Evidence: file:SCHPO/vas2/vas2-uniprot.txt Cytoplasm {ECO:0000269|PubMed:16823372}. Nucleus PMID:19624755 the deletion of any subunit generally caused the disassociation of the heterotetrameric complex from endosomes |
| GO:0005634 nucleus | ISS GO_REF:0000024 | MARK AS OVER ANNOTATED | Summary: Nucleus, transferred (ISS, and its SubCell IEA mapping) from S. pombe Aps1/vas2 (Q9P7N2), whose nuclear and cytoplasmic localization comes only from the genome-wide ORFeome GFP screen. Reason: The only basis is a large-scale GFP-fusion localization in fission yeast (PMID:16823372); the pombe AP-1 study that defined Golgi/endosome localization does not report a nuclear pool, and no S. cerevisiae data place Aps1 or any AP-1 subunit in the nucleus. A diffuse nucleocytoplasmic signal of an over-expressed small fusion is a common screen artefact. AP-1 has no known nuclear function, so the term over-states the evidence. Supporting Evidence: file:SCHPO/vas2/vas2-uniprot.txt Cytoplasm {ECO:0000269|PubMed:16823372}. Nucleus PMID:19624755 the deletion of any subunit generally caused the disassociation of the heterotetrameric complex from endosomes |
| GO:0005737 cytoplasm | IEA GO_REF:0000044 | TOO GENERAL | Summary: Cytoplasm (SubCell mapping and ISS from S. pombe Q9P7N2). Reason: True: Aps1 is a peripheral membrane coat protein recruited from the cytosol to the cytoplasmic face of late Golgi/early endosome membranes. But cytoplasm is entailed by the accepted part_of AP-1 adaptor complex (GO:0030121 is part_of Golgi apparatus, part_of cytoplasm) and by the accepted Golgi apparatus and endosome rows, so it adds nothing. The pombe donor localization is from a genome-wide GFP screen. Supporting Evidence: PMID:26658609 These results indicate that AP-1R localizes primarily to the late Golgi/early endosomes, similar to previous findings placing AP-1 at these compartments file:SCHPO/vas2/vas2-uniprot.txt Cytoplasm {ECO:0000269|PubMed:16823372}. Nucleus |
| GO:0005737 cytoplasm | ISS GO_REF:0000024 | TOO GENERAL | Summary: Cytoplasm (SubCell mapping and ISS from S. pombe Q9P7N2). Reason: True: Aps1 is a peripheral membrane coat protein recruited from the cytosol to the cytoplasmic face of late Golgi/early endosome membranes. But cytoplasm is entailed by the accepted part_of AP-1 adaptor complex (GO:0030121 is part_of Golgi apparatus, part_of cytoplasm) and by the accepted Golgi apparatus and endosome rows, so it adds nothing. The pombe donor localization is from a genome-wide GFP screen. Supporting Evidence: PMID:26658609 These results indicate that AP-1R localizes primarily to the late Golgi/early endosomes, similar to previous findings placing AP-1 at these compartments file:SCHPO/vas2/vas2-uniprot.txt Cytoplasm {ECO:0000269|PubMed:16823372}. Nucleus |
| GO:0005768 endosome | IEA GO_REF:0000044 | ACCEPT | Summary: Endosome (ISS from S. pombe Aps1/vas2 Q9P7N2 and its SubCell IEA mapping). Reason: S. pombe AP-1, including the Aps1 sigma subunit, localizes to endosomes and the complex dissociates from endosomes when any subunit is deleted (PMID:19624755); S. pombe and S. cerevisiae Aps1 are in the same PANTHER subfamily (PTHR11753:SF5), so the transfer is phylogenetically grounded. In S. cerevisiae, AP-1 is placed at late Golgi/early endosomes, and AP-1-dependent cargo (Chs3, Tlg1) cycles between the TGN and early endosomes. Early endosome (GO:0005769) would be more precise, but the yeast TGN and early endosome are not cleanly separable compartments, so endosome is kept as stated. Not directly imaged for S. cerevisiae Aps1. Supporting Evidence: PMID:19624755 the deletion of any subunit generally caused the disassociation of the heterotetrameric complex from endosomes PMID:26658609 These results indicate that AP-1R localizes primarily to the late Golgi/early endosomes, similar to previous findings placing AP-1 at these compartments PMID:11879634 We propose that clathrin and AP-1 act to recycle Chs3p and Tlg1p from the early endosome to the TGN. |
| GO:0005768 endosome | ISS GO_REF:0000024 | ACCEPT | Summary: Endosome (ISS from S. pombe Aps1/vas2 Q9P7N2 and its SubCell IEA mapping). Reason: S. pombe AP-1, including the Aps1 sigma subunit, localizes to endosomes and the complex dissociates from endosomes when any subunit is deleted (PMID:19624755); S. pombe and S. cerevisiae Aps1 are in the same PANTHER subfamily (PTHR11753:SF5), so the transfer is phylogenetically grounded. In S. cerevisiae, AP-1 is placed at late Golgi/early endosomes, and AP-1-dependent cargo (Chs3, Tlg1) cycles between the TGN and early endosomes. Early endosome (GO:0005769) would be more precise, but the yeast TGN and early endosome are not cleanly separable compartments, so endosome is kept as stated. Not directly imaged for S. cerevisiae Aps1. Supporting Evidence: PMID:19624755 the deletion of any subunit generally caused the disassociation of the heterotetrameric complex from endosomes PMID:26658609 These results indicate that AP-1R localizes primarily to the late Golgi/early endosomes, similar to previous findings placing AP-1 at these compartments PMID:11879634 We propose that clathrin and AP-1 act to recycle Chs3p and Tlg1p from the early endosome to the TGN. |
| GO:0005794 Golgi apparatus | IEA GO_REF:0000044 | ACCEPT | Summary: Golgi apparatus (ISS from S. pombe Q9P7N2 and its SubCell IEA mapping). Reason: Consistent with S. cerevisiae data: aps1 deletion genetically interacts with clathrin specifically for Golgi-dependent functions (alpha-factor maturation), and AP-1 localizes to the late Golgi/early endosome (Sec7 compartment). The term is entailed by AP-1 adaptor complex but still carries the organelle information; trans-Golgi network (GO:0005802) would be the precise compartment. Supporting Evidence: PMID:8157009 These results comprise evidence that Aps1p is involved in a subset of clathrin functions at the Golgi apparatus. PMID:26658609 These results indicate that AP-1R localizes primarily to the late Golgi/early endosomes, similar to previous findings placing AP-1 at these compartments |
| GO:0005794 Golgi apparatus | ISS GO_REF:0000024 | ACCEPT | Summary: Golgi apparatus (ISS from S. pombe Q9P7N2 and its SubCell IEA mapping). Reason: Consistent with S. cerevisiae data: aps1 deletion genetically interacts with clathrin specifically for Golgi-dependent functions (alpha-factor maturation), and AP-1 localizes to the late Golgi/early endosome (Sec7 compartment). The term is entailed by AP-1 adaptor complex but still carries the organelle information; trans-Golgi network (GO:0005802) would be the precise compartment. Supporting Evidence: PMID:8157009 These results comprise evidence that Aps1p is involved in a subset of clathrin functions at the Golgi apparatus. PMID:26658609 These results indicate that AP-1R localizes primarily to the late Golgi/early endosomes, similar to previous findings placing AP-1 at these compartments |
| GO:0006886 intracellular protein transport | IEA GO_REF:0000002 | ACCEPT | Summary: Intracellular protein transport, from the clathrin adaptor small-chain InterPro signature. Reason: AP-1 sorts specific membrane-protein cargo between the TGN and endosomes in S. cerevisiae (intracellular retention/recycling of Chs3 and Tlg1; AP-1R-dependent Snc1 sorting, with aps1 deletion increasing surface Snc1 reporter). Aps1 does part of this work as a structural and cargo-recognition subunit of the adaptor. The direction of the relevant step is not settled, so this general term is as precise as the evidence allows. Supporting Evidence: PMID:26658609 Previous studies showed that the AP-1 complex is required for the transport of the chitin synthase Chs3 between Golgi and endosomal compartments PMID:26658609 Loss of APM2, APL4, and APS1 led to a slight but significant increase in GSS surface levels PMID:11879634 We propose that clathrin and AP-1 act to recycle Chs3p and Tlg1p from the early endosome to the TGN. |
| GO:0006896 Golgi to vacuole transport | IMP PMID:17003107 Fab1p and AP-1 are required for trafficking of endogenously ... | KEEP AS NON CORE | Summary: IMP: AP-1 subunit mutants fail to deliver endogenously ubiquitylated cargo to the vacuole lumen (Phelan et al. 2006). Reason: The phenotype is real but the abstract attributes it to a failure to activate Fab1 (PtdIns(3,5)P2 synthesis): Fab1 overexpression restores sorting in AP-1 mutants. AP-1 thus appears to act upstream of, rather than as the carrier for, delivery of ubiquitylated cargo to the vacuole lumen. The curator read the full text (abstract-only cache here) and the term is consistent with AP-1 operating in post-Golgi traffic, so it is retained, but as non-core. Supporting Evidence: PMID:17003107 Like fab1Delta cells, AP-1 complex component mutants have lost the ability to traffic ubiquitylated cargoes to the vacuole lumen PMID:17003107 implying that the protein-sorting defect in these cells is as a result of disruption of PtdIns(3,5)P2 synthesis |
| GO:0010496 intercellular transport | IEA GO_REF:0000117 | REMOVE | Summary: Intercellular transport from an ARBA machine-learning rule. Reason: GO:0010496 intercellular transport is the movement of substances between cells (e.g. via plasmodesmata). Aps1 is an intracellular coat-adaptor subunit of a unicellular fungus; nothing supports cell-to-cell transport. This is a spurious ARBA association. Supporting Evidence: file:yeast/APS1/APS1-uniprot.txt Component of the adapter complexes which link clathrin to |
| GO:0015031 protein transport | IEA GO_REF:0000002 | TOO GENERAL | Summary: Protein transport, from the AP complex small-subunit InterPro signature. Reason: True but entailed by the accepted intracellular protein transport row (GO:0006886 is_a GO:0015031); it adds no information. Supporting Evidence: file:yeast/APS1/APS1-uniprot.txt Belongs to the adaptor complexes small subunit family. PMID:26658609 Previous studies showed that the AP-1 complex is required for the transport of the chitin synthase Chs3 between Golgi and endosomal compartments |
| GO:0016192 vesicle-mediated transport | IBA GO_REF:0000033 | ACCEPT | Summary: IBA from the PANTHER PTHR11753 root node PTN000204281. Reason: Vesicle-mediated transport is true and is the deliberately general term PAINT placed at the family root node PTN000204281 (all AP complex sigma subunits and COPI zeta), where S. cerevisiae APS1 is one of the experimental donors. APS1 is inside that clade, and the yeast data (co-fractionation with clathrin-coated vesicles; AP-1-dependent TGN/endosome cargo sorting) fit it. More specific vesicle-transport steps are not established for Aps1 well enough to replace it, so it is kept as is. Supporting Evidence: PMID:8157009 a significant portion of the Aps proteins co-fractionate with clathrin-coated vesicles during gel filtration chromatography PMID:26658609 Previous studies showed that the AP-1 complex is required for the transport of the chitin synthase Chs3 between Golgi and endosomal compartments |
| GO:0016192 vesicle-mediated transport | IEA GO_REF:0000120 | ACCEPT | Summary: Vesicle-mediated transport from combined InterPro/ARBA IEA. Reason: Vesicle-mediated transport is true and is the deliberately general term PAINT placed at the family root node PTN000204281 (all AP complex sigma subunits and COPI zeta), where S. cerevisiae APS1 is one of the experimental donors. APS1 is inside that clade, and the yeast data (co-fractionation with clathrin-coated vesicles; AP-1-dependent TGN/endosome cargo sorting) fit it. More specific vesicle-transport steps are not established for Aps1 well enough to replace it, so it is kept as is. Supporting Evidence: PMID:8157009 a significant portion of the Aps proteins co-fractionate with clathrin-coated vesicles during gel filtration chromatography file:yeast/APS1/APS1-uniprot.txt Belongs to the adaptor complexes small subunit family. |
| GO:0030117 membrane coat | IEA GO_REF:0000002 | TOO GENERAL | Summary: Membrane coat, from the clathrin adaptor small-chain InterPro signature. Reason: True: AP-1 is a clathrin coat adaptor. But GO:0030121 AP-1 adaptor complex, accepted here with experimental support, is_a clathrin adaptor complex / clathrin vesicle coat / membrane coat, so this row adds nothing. Supporting Evidence: PMID:10564262 Using coimmunoprecipitation, the subunit composition of two complexes, AP-1 and AP-2R, has been defined. |
| GO:0030121 AP-1 adaptor complex | EXP PMID:10564262 Adaptor complex-independent clathrin function in yeast. | ACCEPT | Summary: EXP: Aps1 is a subunit of the AP-1 complex (co-immunoprecipitation). Reason: Aps1 co-immunoprecipitates with the other AP-1 subunits (Apl2, Apl4, Apm1) and AP-1 is the only yeast AP complex that binds clathrin (Yeung et al. 1999). Aps1 is also the shared sigma subunit of the AP-1R variant (Apm2 in place of Apm1). This is the best-established fact about Aps1 in S. cerevisiae and the core of its function. Supporting Evidence: PMID:10564262 Using coimmunoprecipitation, the subunit composition of two complexes, AP-1 and AP-2R, has been defined. PMID:10564262 As assessed by in vitro binding assays and coimmunoprecipitation, only AP-1 interacts with clathrin. PMID:26658609 The two forms of AP-1 share the same large (Apl2 and Apl4) and small (Aps1) subunits but incorporate different medium subunits (Apm1 or Apm2). |
| GO:0030121 AP-1 adaptor complex | IDA PMID:10564262 Adaptor complex-independent clathrin function in yeast. | ACCEPT | Summary: IDA: Aps1 is a subunit of the AP-1 complex (co-immunoprecipitation). Reason: Aps1 co-immunoprecipitates with the other AP-1 subunits (Apl2, Apl4, Apm1) and AP-1 is the only yeast AP complex that binds clathrin (Yeung et al. 1999). Aps1 is also the shared sigma subunit of the AP-1R variant (Apm2 in place of Apm1). This is the best-established fact about Aps1 in S. cerevisiae and the core of its function. Supporting Evidence: PMID:10564262 Using coimmunoprecipitation, the subunit composition of two complexes, AP-1 and AP-2R, has been defined. PMID:10564262 As assessed by in vitro binding assays and coimmunoprecipitation, only AP-1 interacts with clathrin. PMID:26658609 The two forms of AP-1 share the same large (Apl2 and Apl4) and small (Aps1) subunits but incorporate different medium subunits (Apm1 or Apm2). |
| GO:0030121 AP-1 adaptor complex | IEA GO_REF:0000120 | ACCEPT | Summary: AP-1 adaptor complex, from AP1_sigma InterPro signature plus ARBA. Reason: Aps1 co-immunoprecipitates with the other AP-1 subunits (Apl2, Apl4, Apm1) and AP-1 is the only yeast AP complex that binds clathrin (Yeung et al. 1999). Aps1 is also the shared sigma subunit of the AP-1R variant (Apm2 in place of Apm1). This is the best-established fact about Aps1 in S. cerevisiae and the core of its function. Supporting Evidence: PMID:10564262 Using coimmunoprecipitation, the subunit composition of two complexes, AP-1 and AP-2R, has been defined. PMID:8157009 Aps1p is more similar to the sigma subunit of the Golgi-localized mammalian AP-1 complex than Aps2p |
| GO:0030121 AP-1 adaptor complex | NAS PMID:10564262 Adaptor complex-independent clathrin function in yeast. | ACCEPT | Summary: NAS: Aps1 as AP-1 subunit (ComplexPortal-style statement). Reason: Aps1 co-immunoprecipitates with the other AP-1 subunits (Apl2, Apl4, Apm1) and AP-1 is the only yeast AP complex that binds clathrin (Yeung et al. 1999). Aps1 is also the shared sigma subunit of the AP-1R variant (Apm2 in place of Apm1). This is the best-established fact about Aps1 in S. cerevisiae and the core of its function. Supporting Evidence: PMID:10564262 Using coimmunoprecipitation, the subunit composition of two complexes, AP-1 and AP-2R, has been defined. PMID:26658609 The two forms of AP-1 share the same large (Apl2 and Apl4) and small (Aps1) subunits but incorporate different medium subunits (Apm1 or Apm2). |
| GO:0030665 clathrin-coated vesicle membrane | IEA GO_REF:0000044 | ACCEPT | Summary: Clathrin-coated vesicle membrane (SubCell mapping; UniProt cites S. pombe Q9P7N2). Reason: Directly supported in S. cerevisiae: a significant fraction of Aps1 co-fractionates with clathrin-coated vesicles on gel filtration (Phan et al. 1994), and AP-1 binds clathrin. AP-1 is part_of the CCV coat, so this location is expected for a sigma1 subunit. Supporting Evidence: PMID:8157009 a significant portion of the Aps proteins co-fractionate with clathrin-coated vesicles during gel filtration chromatography PMID:10564262 As assessed by in vitro binding assays and coimmunoprecipitation, only AP-1 interacts with clathrin. |
| GO:0035615 clathrin-cargo adaptor activity | IEA GO_REF:0000002 | ACCEPT | Summary: Clathrin-cargo adaptor activity, from the AP1_sigma InterPro signature (IPR044733). Reason: Aps1 belongs to the AP-1 sigma subfamily, and the yeast AP-1 complex links clathrin to cargo: it is the only yeast AP complex that binds clathrin, and its gamma/sigma hemicomplex recognises the dileucine signal that sorts Chs3. The activity is a property of the heterotetramer to which Aps1 contributes; it has not been reconstituted for Aps1 alone. Yeast AP-1 is also notably dispensable for bulk clathrin function under normal conditions. Supporting Evidence: PMID:10564262 As assessed by in vitro binding assays and coimmunoprecipitation, only AP-1 interacts with clathrin. PMID:26658609 Because the dileucine-based motif of Chs3 binds the Ξ³/Ο subunits present in both AP-1 and AP-1R PMID:10564262 We conclude that AP complexes are dispensable for clathrin function in S. cerevisiae under normal conditions. |
Loading supporting contentβ¦
Download this section (compressed HTML)Q: Does Aps1 directly contact the Chs3 dileucine signal in the yeast AP-1 complex, as the gamma/sigma hemicomplex does in mammals, or is cargo recognition in yeast AP-1 mediated differently?
Q: Is the AP-1-dependent Fab1 activation (PtdIns(3,5)P2 synthesis) a direct effect of AP-1 vesicles delivering Fab1/Vac14 complex components, or an indirect effect of missorted cargo?
Experiment: Mutate the conserved dileucine-binding pocket residues of Aps1 (by structural alignment to mammalian sigma1) and test Chs3 retention in chs6 cells and Snc1 reporter sorting, to separate Aps1 cargo-recognition from complex-assembly roles.
Type: site-directed mutagenesis with cargo-sorting assays
Small subunit of the clathrin-associated adaptor complex AP-1; AP-1 is involved in protein sorting at the trans-Golgi network; homolog of the sigma subunit of the mammalian clathrin AP-1 complex
Loading supporting contentβ¦
Download this section (compressed HTML)Loading supporting contentβ¦
Download this section (compressed HTML)