DNAJC6 (auxilin, auxilin-1) is a neuronally enriched DnaJ/HSP40 co-chaperone that drives the HSC70/HSPA8-dependent uncoating of clathrin-coated vesicles. It is a multidomain protein comprising an N-terminal PTEN-like tensin-type phosphatase domain and a C2 domain (a phosphoinositide-binding membrane-targeting module that is thought to be catalytically degenerate), a long disordered clathrin-binding region, and a C-terminal J domain. Auxilin binds clathrin cages stoichiometrically (one per triskelion) and, through its J domain, recruits HSPA8/HSC70 and stimulates its ATPase activity to dismantle the clathrin lattice, thereby promoting clathrin-mediated endocytosis and the recycling/uncoating of synaptic vesicles at nerve terminals. Loss-of-function mutations cause autosomal-recessive juvenile- and early-onset Parkinson disease (PARK19A/PARK19B) through impaired synaptic vesicle endocytosis in dopaminergic neurons.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0030276 clathrin binding | IBA GO_REF:0000033 | ACCEPT | Summary: Auxilin binds clathrin cages stoichiometrically, the recognition step that targets HSC70 to clathrin-coated vesicles. A core molecular function. Reason: Direct clathrin binding by auxilin is well established (binds clathrin cages at one auxilin per triskelion) and is essential for its uncoating role. Supporting Evidence: file:human/DNAJC6/DNAJC6-uniprot.txt binds tightly to the clathrin cages, at a |
| GO:0031982 vesicle | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: Auxilin acts on clathrin-coated vesicles; vesicle is a correct but generic compartment. Reason: Correct but generic; the specific functional compartment is the clathrin-coated vesicle. Supporting Evidence: file:human/DNAJC6/DNAJC6-uniprot.txt clathrin-coated vesicle |
| GO:0014069 postsynaptic density | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: Phylogenetic inference of postsynaptic density localization. Auxilin's best-established functional site is presynaptic endocytosis of synaptic vesicles. Reason: A plausible neuronal localization by family inference, but auxilin's characterized role is in presynaptic clathrin-mediated synaptic vesicle endocytosis rather than the postsynaptic density; retained as non-core. Supporting Evidence: file:human/DNAJC6/DNAJC6-goa.tsv postsynaptic density |
| GO:0016191 synaptic vesicle uncoating | IBA GO_REF:0000033 | ACCEPT | Summary: Auxilin mediates HSC70-dependent uncoating of clathrin from synaptic vesicles, a core biological process. Reason: Strongly supported by auxilin's role as the cofactor for HSC70-mediated clathrin uncoating and by the synaptic phenotype of auxilin-knockout mice. Supporting Evidence: PMID:20160091 act as cochaperones to support the Hsc70-dependent clathrin uncoating of clathrin-coated vesicles |
| GO:0030136 clathrin-coated vesicle | IEA GO_REF:0000044 | ACCEPT | Summary: Clathrin-coated vesicle localization, the core functional compartment where auxilin recruits HSC70 to drive uncoating. Reason: Auxilin appears on coated vesicles in transient bursts after vesicle release; this is its principal site of action. Supporting Evidence: file:human/DNAJC6/DNAJC6-uniprot.txt SUBCELLULAR LOCATION: Cytoplasmic vesicle, clathrin-coated vesicle |
| GO:1905443 regulation of clathrin coat assembly | IEA GO_REF:0000117 | ACCEPT | Summary: Auxilin regulates clathrin coat assembly/disassembly; its depletion causes accumulation of nonproductive clathrin cages. Reason: Supported experimentally by IMP evidence (PMID:18489706) showing auxilin depletion alters clathrin coat formation. Supporting Evidence: file:human/DNAJC6/DNAJC6-uniprot.txt prevent the formation of nonproductive clathrin cages |
| GO:0014069 postsynaptic density | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: Ensembl-projected postsynaptic density localization from the mouse ortholog. Reason: As for the IBA postsynaptic density annotation, plausible but not auxilin's core presynaptic functional site. Supporting Evidence: file:human/DNAJC6/DNAJC6-goa.tsv postsynaptic density |
| GO:0016191 synaptic vesicle uncoating | IEA GO_REF:0000107 | ACCEPT | Summary: Ensembl-projected synaptic vesicle uncoating, redundant with the IBA and ISS annotations of the same process. Reason: Core auxilin process; redundant with stronger evidence for the same term. Supporting Evidence: PMID:20160091 act as cochaperones to support the Hsc70-dependent clathrin uncoating of clathrin-coated vesicles |
| GO:0036465 synaptic vesicle recycling | IEA GO_REF:0000107 | ACCEPT | Summary: Auxilin participates in synaptic vesicle recycling by uncoating clathrin during endocytic retrieval, projected from the mouse ortholog. Reason: Supported by the synaptic phenotype of auxilin-knockout mice showing impaired clathrin-mediated synaptic vesicle endocytosis and recycling. Supporting Evidence: PMID:20160091 the specialized role of auxilin in the recycling of synaptic vesicles at synapses |
| GO:0045202 synapse | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: Synapse localization projected from the mouse ortholog; auxilin acts at presynaptic endocytic zones. Reason: Correct neuronal compartment but generic; the more specific site is the presynaptic endocytic zone / clathrin-coated vesicle. Supporting Evidence: file:human/DNAJC6/DNAJC6-uniprot.txt synaptic vesicles |
| GO:0072583 clathrin-dependent endocytosis | IEA GO_REF:0000120 | ACCEPT | Summary: Auxilin participates in clathrin-mediated/clathrin-dependent endocytosis, here from automated annotation; corroborated by direct IMP evidence. Reason: Core auxilin process, directly demonstrated by RNAi (PMID:18489706); redundant with the IMP annotation. Supporting Evidence: file:human/DNAJC6/DNAJC6-uniprot.txt participates in clathrin-mediated endocytosis of synaptic vesicles |
| GO:0098894 extrinsic component of presynaptic endocytic zone membrane | IEA GO_REF:0000107 | ACCEPT | Summary: Localization to the presynaptic endocytic zone membrane (extrinsic component), projected from the mouse ortholog; matches auxilin's role in synaptic vesicle endocytosis. Reason: A specific and accurate functional localization for auxilin, where it acts on clathrin-coated pits/vesicles at the presynaptic endocytic zone. Supporting Evidence: file:human/DNAJC6/DNAJC6-uniprot.txt clathrin-mediated endocytosis of synaptic vesicles |
| GO:0072583 clathrin-dependent endocytosis | ISS GO_REF:0000024 | ACCEPT | Summary: ISS clathrin-dependent endocytosis from the Drosophila ortholog, redundant with the IMP and IEA annotations. Reason: Core process; redundant with directly demonstrated evidence. Supporting Evidence: file:human/DNAJC6/DNAJC6-uniprot.txt participates in clathrin-mediated endocytosis of synaptic vesicles |
| GO:0005515 protein binding | IPI PMID:29735704 LRRK2 phosphorylation of auxilin mediates synaptic defects i... | MODIFY | Summary: IPI capture of the auxilin-CLTC (clathrin heavy chain, Q00610) interaction. The bare protein binding term is uninformative; this interaction reflects auxilin's clathrin heavy chain binding. Reason: Per curation guidelines bare protein binding is uninformative. The WITH partner is CLTC (clathrin heavy chain, Q00610), so the specific molecular function is clathrin heavy chain binding. Proposed replacements: clathrin heavy chain binding Supporting Evidence: file:human/DNAJC6/DNAJC6-uniprot.txt Interacts with CLTC |
| GO:0031072 heat shock protein binding | ISS GO_REF:0000024 | ACCEPT | Summary: Auxilin binds the heat shock protein HSPA8/HSC70 in an ATP-dependent manner and stimulates its ATPase activity; this HSP70 co-chaperone function is core. Reason: The J-domain-mediated interaction with HSPA8/HSC70 is central to auxilin's uncoating mechanism and is well documented. Supporting Evidence: file:human/DNAJC6/DNAJC6-uniprot.txt Interacts with HSPA8/HSC70 in an ATP-dependent manner; this interaction stimulates the HSPA8's ATPase activity |
| GO:0032050 clathrin heavy chain binding | ISS GO_REF:0000024 | ACCEPT | Summary: Auxilin binds the clathrin heavy chain (CLTC), producing local changes in heavy-chain contacts; a core molecular function. Reason: Directly supported by the auxilin-CLTC interaction (also captured by IPI) that distorts the clathrin coat to enable disassembly. Supporting Evidence: file:human/DNAJC6/DNAJC6-uniprot.txt Interacts with CLTC; this interaction produces a local change in heavy-chain contacts |
| GO:0072318 clathrin coat disassembly | ISS GO_REF:0000024 | ACCEPT | Summary: Auxilin drives disassembly of the clathrin coat by recruiting HSPA8 and triggering ATP-hydrolysis-driven dismantling of the cage; a core process. Reason: Central mechanism of auxilin; the J domain is required for basket dissociation. Supporting Evidence: file:human/DNAJC6/DNAJC6-uniprot.txt concerted dismantling of the cage into component triskelia |
| GO:0072583 clathrin-dependent endocytosis | IMP PMID:18489706 Auxilin depletion causes self-assembly of clathrin into memb... | ACCEPT | Summary: RNAi depletion of auxilins inhibits clathrin-mediated endocytosis, providing direct experimental evidence for auxilin's role. Reason: Directly demonstrated by mutant-phenotype evidence; a core auxilin process. Supporting Evidence: PMID:18489706 both auxilins need to be depleted for inhibition of clathrin-mediated endocytosis |
| GO:1905443 regulation of clathrin coat assembly | IMP PMID:18489706 Auxilin depletion causes self-assembly of clathrin into memb... | ACCEPT | Summary: Auxilin depletion causes accumulation of nonproductive clathrin cages, showing auxilin regulates clathrin coat assembly/turnover. Reason: Directly supported by the depletion phenotype (self-assembly of clathrin into membraneless cages). Supporting Evidence: PMID:18489706 prevent the formation of nonproductive clathrin cages in the cytosol |
| GO:0030136 clathrin-coated vesicle | ISS GO_REF:0000024 | ACCEPT | Summary: ISS clathrin-coated vesicle localization, redundant with the IEA annotation. Reason: Core functional compartment; redundant with stronger evidence. Supporting Evidence: file:human/DNAJC6/DNAJC6-uniprot.txt SUBCELLULAR LOCATION: Cytoplasmic vesicle, clathrin-coated vesicle |
| GO:0030276 clathrin binding | ISS GO_REF:0000024 | ACCEPT | Summary: ISS clathrin binding from the Drosophila ortholog, redundant with the IBA annotation. Reason: Core molecular function; redundant with the IBA clathrin binding annotation. Supporting Evidence: file:human/DNAJC6/DNAJC6-uniprot.txt binds tightly to the clathrin cages, at a |
| GO:0036465 synaptic vesicle recycling | ISS GO_REF:0000024 | ACCEPT | Summary: ISS synaptic vesicle recycling from the mouse ortholog, redundant with the IEA annotation. Reason: Core auxilin process; redundant with the knockout-supported annotation. Supporting Evidence: PMID:20160091 the specialized role of auxilin in the recycling of synaptic vesicles at synapses |
| GO:0016191 synaptic vesicle uncoating | ISS PMID:20160091 Endocytosis and clathrin-uncoating defects at synapses of au... | ACCEPT | Summary: ISS synaptic vesicle uncoating based on the auxilin-knockout mouse, demonstrating auxilin's specialized synaptic uncoating role. Reason: Strongly supported by the knockout phenotype showing endocytosis and clathrin-uncoating defects at synapses. Supporting Evidence: PMID:20160091 Endocytosis and clathrin-uncoating defects at synapses of auxilin knockout mice |
| GO:0005829 cytosol | TAS Reactome:R-HSA-421836 | KEEP AS NON CORE | Summary: Reactome cytosol localization for auxilin (clathrin-mediated endocytosis pathway); auxilin cycles between a soluble cytosolic pool and clathrin coats. Reason: Auxilin has a genuine cytosolic pool from which it is recruited to coated vesicles, but the cytosol localization is less informative than its clathrin-coated-vesicle site of action; one of several redundant Reactome cytosol annotations. Supporting Evidence: file:human/DNAJC6/DNAJC6-goa.tsv cytosol |
| GO:0005829 cytosol | TAS Reactome:R-HSA-432688 | KEEP AS NON CORE | Summary: Redundant Reactome cytosol localization (vesicle biogenesis pathway). Reason: Redundant cytosol annotation; genuine but non-core. Supporting Evidence: file:human/DNAJC6/DNAJC6-goa.tsv cytosol |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8868658 | KEEP AS NON CORE | Summary: Redundant Reactome cytosol localization. Reason: Redundant cytosol annotation; genuine but non-core. Supporting Evidence: file:human/DNAJC6/DNAJC6-goa.tsv cytosol |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8868659 | KEEP AS NON CORE | Summary: Redundant Reactome cytosol localization. Reason: Redundant cytosol annotation; genuine but non-core. Supporting Evidence: file:human/DNAJC6/DNAJC6-goa.tsv cytosol |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8868660 | KEEP AS NON CORE | Summary: Redundant Reactome cytosol localization. Reason: Redundant cytosol annotation; genuine but non-core. Supporting Evidence: file:human/DNAJC6/DNAJC6-goa.tsv cytosol |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8869438 | KEEP AS NON CORE | Summary: Redundant Reactome cytosol localization. Reason: Redundant cytosol annotation; genuine but non-core. Supporting Evidence: file:human/DNAJC6/DNAJC6-goa.tsv cytosol |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8871193 | KEEP AS NON CORE | Summary: Redundant Reactome cytosol localization. Reason: Redundant cytosol annotation; genuine but non-core. Supporting Evidence: file:human/DNAJC6/DNAJC6-goa.tsv cytosol |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8871194 | KEEP AS NON CORE | Summary: Redundant Reactome cytosol localization. Reason: Redundant cytosol annotation; genuine but non-core. Supporting Evidence: file:human/DNAJC6/DNAJC6-goa.tsv cytosol |
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Download this section (compressed HTML)Q: Is the PTEN-like phosphatase domain of auxilin catalytically active, or does it function purely as a phosphoinositide-binding membrane-targeting module that times auxilin recruitment to coated vesicles?
Q: How does LRRK2-mediated phosphorylation of auxilin's clathrin-binding domain mechanistically convert into the synaptic vesicle endocytosis defects seen in Parkinson disease dopaminergic neurons?
Q: To what extent can the ubiquitous homolog GAK compensate for neuronal auxilin loss, and does incomplete compensation explain the dopaminergic-neuron vulnerability in PARK19?
Experiment: Reconstituted clathrin-cage disassembly assays with purified auxilin (wild-type, J-domain HPD mutant, and PARK19 disease variants) plus HSPA8 and ATP to quantify uncoating activity and HSPA8 ATPase stimulation.
Experiment: Phosphatase activity assays on the auxilin PTEN-like domain against phosphoprotein and phosphoinositide substrates, with active-site (Cys164) mutants, to resolve whether it is a bona fide phosphatase or a degenerate lipid-binding domain.
Experiment: Live-cell imaging of clathrin and HSC70 dynamics in DNAJC6-knockout versus rescued neurons (wild-type vs PARK19 variants) to map the uncoating defect and test GAK compensation.
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