id: O75061 gene_symbol: DNAJC6 product_type: PROTEIN status: COMPLETE taxon: id: NCBITaxon:9606 label: Homo sapiens description: 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. alternative_products: - name: '1' id: O75061-1 - name: '2' id: O75061-2 sequence_note: VSP_019580 - name: '3' id: O75061-3 sequence_note: VSP_019579, VSP_019581 - name: '4' id: O75061-4 sequence_note: VSP_019579 existing_annotations: - term: id: GO:0030276 label: clathrin binding evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: enables review: summary: Auxilin binds clathrin cages stoichiometrically, the recognition step that targets HSC70 to clathrin-coated vesicles. A core molecular function. action: ACCEPT reason: Direct clathrin binding by auxilin is well established (binds clathrin cages at one auxilin per triskelion) and is essential for its uncoating role. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-uniprot.txt supporting_text: binds tightly to the clathrin cages, at a - term: id: GO:0031982 label: vesicle evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: is_active_in review: summary: Auxilin acts on clathrin-coated vesicles; vesicle is a correct but generic compartment. action: KEEP_AS_NON_CORE reason: Correct but generic; the specific functional compartment is the clathrin-coated vesicle. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-uniprot.txt supporting_text: clathrin-coated vesicle - term: id: GO:0014069 label: postsynaptic density evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: is_active_in review: summary: Phylogenetic inference of postsynaptic density localization. Auxilin's best-established functional site is presynaptic endocytosis of synaptic vesicles. action: KEEP_AS_NON_CORE 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. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-goa.tsv supporting_text: postsynaptic density - term: id: GO:0016191 label: synaptic vesicle uncoating evidence_type: IBA original_reference_id: GO_REF:0000033 qualifier: involved_in review: summary: Auxilin mediates HSC70-dependent uncoating of clathrin from synaptic vesicles, a core biological process. action: ACCEPT reason: Strongly supported by auxilin's role as the cofactor for HSC70-mediated clathrin uncoating and by the synaptic phenotype of auxilin-knockout mice. supported_by: - reference_id: PMID:20160091 supporting_text: act as cochaperones to support the Hsc70-dependent clathrin uncoating of clathrin-coated vesicles - term: id: GO:0030136 label: clathrin-coated vesicle evidence_type: IEA original_reference_id: GO_REF:0000044 qualifier: located_in review: summary: Clathrin-coated vesicle localization, the core functional compartment where auxilin recruits HSC70 to drive uncoating. action: ACCEPT reason: Auxilin appears on coated vesicles in transient bursts after vesicle release; this is its principal site of action. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-uniprot.txt supporting_text: 'SUBCELLULAR LOCATION: Cytoplasmic vesicle, clathrin-coated vesicle' - term: id: GO:1905443 label: regulation of clathrin coat assembly evidence_type: IEA original_reference_id: GO_REF:0000117 qualifier: involved_in review: summary: Auxilin regulates clathrin coat assembly/disassembly; its depletion causes accumulation of nonproductive clathrin cages. action: ACCEPT reason: Supported experimentally by IMP evidence (PMID:18489706) showing auxilin depletion alters clathrin coat formation. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-uniprot.txt supporting_text: prevent the formation of nonproductive clathrin cages - term: id: GO:0014069 label: postsynaptic density evidence_type: IEA original_reference_id: GO_REF:0000107 qualifier: located_in review: summary: Ensembl-projected postsynaptic density localization from the mouse ortholog. action: KEEP_AS_NON_CORE reason: As for the IBA postsynaptic density annotation, plausible but not auxilin's core presynaptic functional site. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-goa.tsv supporting_text: postsynaptic density - term: id: GO:0016191 label: synaptic vesicle uncoating evidence_type: IEA original_reference_id: GO_REF:0000107 qualifier: involved_in review: summary: Ensembl-projected synaptic vesicle uncoating, redundant with the IBA and ISS annotations of the same process. action: ACCEPT reason: Core auxilin process; redundant with stronger evidence for the same term. supported_by: - reference_id: PMID:20160091 supporting_text: act as cochaperones to support the Hsc70-dependent clathrin uncoating of clathrin-coated vesicles - term: id: GO:0036465 label: synaptic vesicle recycling evidence_type: IEA original_reference_id: GO_REF:0000107 qualifier: involved_in review: summary: Auxilin participates in synaptic vesicle recycling by uncoating clathrin during endocytic retrieval, projected from the mouse ortholog. action: ACCEPT reason: Supported by the synaptic phenotype of auxilin-knockout mice showing impaired clathrin-mediated synaptic vesicle endocytosis and recycling. supported_by: - reference_id: PMID:20160091 supporting_text: the specialized role of auxilin in the recycling of synaptic vesicles at synapses - term: id: GO:0045202 label: synapse evidence_type: IEA original_reference_id: GO_REF:0000107 qualifier: located_in review: summary: Synapse localization projected from the mouse ortholog; auxilin acts at presynaptic endocytic zones. action: KEEP_AS_NON_CORE reason: Correct neuronal compartment but generic; the more specific site is the presynaptic endocytic zone / clathrin-coated vesicle. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-uniprot.txt supporting_text: synaptic vesicles - term: id: GO:0072583 label: clathrin-dependent endocytosis evidence_type: IEA original_reference_id: GO_REF:0000120 qualifier: involved_in review: summary: Auxilin participates in clathrin-mediated/clathrin-dependent endocytosis, here from automated annotation; corroborated by direct IMP evidence. action: ACCEPT reason: Core auxilin process, directly demonstrated by RNAi (PMID:18489706); redundant with the IMP annotation. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-uniprot.txt supporting_text: participates in clathrin-mediated endocytosis of synaptic vesicles - term: id: GO:0098894 label: extrinsic component of presynaptic endocytic zone membrane evidence_type: IEA original_reference_id: GO_REF:0000107 qualifier: is_active_in review: summary: Localization to the presynaptic endocytic zone membrane (extrinsic component), projected from the mouse ortholog; matches auxilin's role in synaptic vesicle endocytosis. action: ACCEPT reason: A specific and accurate functional localization for auxilin, where it acts on clathrin-coated pits/vesicles at the presynaptic endocytic zone. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-uniprot.txt supporting_text: clathrin-mediated endocytosis of synaptic vesicles - term: id: GO:0072583 label: clathrin-dependent endocytosis evidence_type: ISS original_reference_id: GO_REF:0000024 qualifier: involved_in review: summary: ISS clathrin-dependent endocytosis from the Drosophila ortholog, redundant with the IMP and IEA annotations. action: ACCEPT reason: Core process; redundant with directly demonstrated evidence. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-uniprot.txt supporting_text: participates in clathrin-mediated endocytosis of synaptic vesicles - term: id: GO:0005515 label: protein binding evidence_type: IPI original_reference_id: PMID:29735704 qualifier: enables review: 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. action: MODIFY 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_replacement_terms: - id: GO:0032050 label: clathrin heavy chain binding supported_by: - reference_id: file:human/DNAJC6/DNAJC6-uniprot.txt supporting_text: Interacts with CLTC - term: id: GO:0031072 label: heat shock protein binding evidence_type: ISS original_reference_id: GO_REF:0000024 qualifier: enables review: 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. action: ACCEPT reason: The J-domain-mediated interaction with HSPA8/HSC70 is central to auxilin's uncoating mechanism and is well documented. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-uniprot.txt supporting_text: Interacts with HSPA8/HSC70 in an ATP-dependent manner; this interaction stimulates the HSPA8's ATPase activity - term: id: GO:0032050 label: clathrin heavy chain binding evidence_type: ISS original_reference_id: GO_REF:0000024 qualifier: enables review: summary: Auxilin binds the clathrin heavy chain (CLTC), producing local changes in heavy-chain contacts; a core molecular function. action: ACCEPT reason: Directly supported by the auxilin-CLTC interaction (also captured by IPI) that distorts the clathrin coat to enable disassembly. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-uniprot.txt supporting_text: Interacts with CLTC; this interaction produces a local change in heavy-chain contacts - term: id: GO:0072318 label: clathrin coat disassembly evidence_type: ISS original_reference_id: GO_REF:0000024 qualifier: involved_in review: summary: Auxilin drives disassembly of the clathrin coat by recruiting HSPA8 and triggering ATP-hydrolysis-driven dismantling of the cage; a core process. action: ACCEPT reason: Central mechanism of auxilin; the J domain is required for basket dissociation. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-uniprot.txt supporting_text: concerted dismantling of the cage into component triskelia - term: id: GO:0072583 label: clathrin-dependent endocytosis evidence_type: IMP original_reference_id: PMID:18489706 qualifier: involved_in review: summary: RNAi depletion of auxilins inhibits clathrin-mediated endocytosis, providing direct experimental evidence for auxilin's role. action: ACCEPT reason: Directly demonstrated by mutant-phenotype evidence; a core auxilin process. supported_by: - reference_id: PMID:18489706 supporting_text: both auxilins need to be depleted for inhibition of clathrin-mediated endocytosis - term: id: GO:1905443 label: regulation of clathrin coat assembly evidence_type: IMP original_reference_id: PMID:18489706 qualifier: involved_in review: summary: Auxilin depletion causes accumulation of nonproductive clathrin cages, showing auxilin regulates clathrin coat assembly/turnover. action: ACCEPT reason: Directly supported by the depletion phenotype (self-assembly of clathrin into membraneless cages). supported_by: - reference_id: PMID:18489706 supporting_text: prevent the formation of nonproductive clathrin cages in the cytosol - term: id: GO:0030136 label: clathrin-coated vesicle evidence_type: ISS original_reference_id: GO_REF:0000024 qualifier: located_in review: summary: ISS clathrin-coated vesicle localization, redundant with the IEA annotation. action: ACCEPT reason: Core functional compartment; redundant with stronger evidence. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-uniprot.txt supporting_text: 'SUBCELLULAR LOCATION: Cytoplasmic vesicle, clathrin-coated vesicle' - term: id: GO:0030276 label: clathrin binding evidence_type: ISS original_reference_id: GO_REF:0000024 qualifier: enables review: summary: ISS clathrin binding from the Drosophila ortholog, redundant with the IBA annotation. action: ACCEPT reason: Core molecular function; redundant with the IBA clathrin binding annotation. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-uniprot.txt supporting_text: binds tightly to the clathrin cages, at a - term: id: GO:0036465 label: synaptic vesicle recycling evidence_type: ISS original_reference_id: GO_REF:0000024 qualifier: involved_in review: summary: ISS synaptic vesicle recycling from the mouse ortholog, redundant with the IEA annotation. action: ACCEPT reason: Core auxilin process; redundant with the knockout-supported annotation. supported_by: - reference_id: PMID:20160091 supporting_text: the specialized role of auxilin in the recycling of synaptic vesicles at synapses - term: id: GO:0016191 label: synaptic vesicle uncoating evidence_type: ISS original_reference_id: PMID:20160091 qualifier: involved_in review: summary: ISS synaptic vesicle uncoating based on the auxilin-knockout mouse, demonstrating auxilin's specialized synaptic uncoating role. action: ACCEPT reason: Strongly supported by the knockout phenotype showing endocytosis and clathrin-uncoating defects at synapses. supported_by: - reference_id: PMID:20160091 supporting_text: Endocytosis and clathrin-uncoating defects at synapses of auxilin knockout mice - term: id: GO:0005829 label: cytosol evidence_type: TAS original_reference_id: Reactome:R-HSA-421836 qualifier: located_in review: summary: Reactome cytosol localization for auxilin (clathrin-mediated endocytosis pathway); auxilin cycles between a soluble cytosolic pool and clathrin coats. action: KEEP_AS_NON_CORE 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. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-goa.tsv supporting_text: cytosol - term: id: GO:0005829 label: cytosol evidence_type: TAS original_reference_id: Reactome:R-HSA-432688 qualifier: located_in review: summary: Redundant Reactome cytosol localization (vesicle biogenesis pathway). action: KEEP_AS_NON_CORE reason: Redundant cytosol annotation; genuine but non-core. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-goa.tsv supporting_text: cytosol - term: id: GO:0005829 label: cytosol evidence_type: TAS original_reference_id: Reactome:R-HSA-8868658 qualifier: located_in review: summary: Redundant Reactome cytosol localization. action: KEEP_AS_NON_CORE reason: Redundant cytosol annotation; genuine but non-core. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-goa.tsv supporting_text: cytosol - term: id: GO:0005829 label: cytosol evidence_type: TAS original_reference_id: Reactome:R-HSA-8868659 qualifier: located_in review: summary: Redundant Reactome cytosol localization. action: KEEP_AS_NON_CORE reason: Redundant cytosol annotation; genuine but non-core. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-goa.tsv supporting_text: cytosol - term: id: GO:0005829 label: cytosol evidence_type: TAS original_reference_id: Reactome:R-HSA-8868660 qualifier: located_in review: summary: Redundant Reactome cytosol localization. action: KEEP_AS_NON_CORE reason: Redundant cytosol annotation; genuine but non-core. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-goa.tsv supporting_text: cytosol - term: id: GO:0005829 label: cytosol evidence_type: TAS original_reference_id: Reactome:R-HSA-8869438 qualifier: located_in review: summary: Redundant Reactome cytosol localization. action: KEEP_AS_NON_CORE reason: Redundant cytosol annotation; genuine but non-core. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-goa.tsv supporting_text: cytosol - term: id: GO:0005829 label: cytosol evidence_type: TAS original_reference_id: Reactome:R-HSA-8871193 qualifier: located_in review: summary: Redundant Reactome cytosol localization. action: KEEP_AS_NON_CORE reason: Redundant cytosol annotation; genuine but non-core. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-goa.tsv supporting_text: cytosol - term: id: GO:0005829 label: cytosol evidence_type: TAS original_reference_id: Reactome:R-HSA-8871194 qualifier: located_in review: summary: Redundant Reactome cytosol localization. action: KEEP_AS_NON_CORE reason: Redundant cytosol annotation; genuine but non-core. supported_by: - reference_id: file:human/DNAJC6/DNAJC6-goa.tsv supporting_text: cytosol references: - id: GO_REF:0000024 title: Manual transfer of experimentally-verified manual GO annotation data to orthologs using Ensembl Compara findings: [] - id: GO_REF:0000033 title: Annotation inferences using phylogenetic trees findings: [] - id: GO_REF:0000044 title: Gene Ontology annotation through association of InterPro records with GO terms findings: [] - id: GO_REF:0000107 title: Automatic transfer of experimentally verified manual GO annotation data to orthologs using Ensembl Compara findings: [] - id: GO_REF:0000117 title: Electronic Gene Ontology annotations created by ARBA machine learning models findings: [] - id: GO_REF:0000120 title: Combined Automated Annotation using Multiple IEA Methods findings: [] - id: PMID:18489706 title: Auxilin depletion causes self-assembly of clathrin into membraneless cages in vivo. reference_review: relevance: HIGH correctness: VERIFIED review_notes: "Cached publication (publications/PMID_18489706.md) PubMed title matches the YAML title exactly; abstract states auxilin is a cofactor for HSC70-mediated uncoating of clathrin-coated vesicles and that depletion blocks clathrin-mediated endocytosis, directly supporting DNAJC6's clathrin-uncoating co-chaperone core function." findings: - statement: Auxilin is a cofactor for HSC70-mediated uncoating of clathrin-coated vesicles; depletion of both auxilin isoforms inhibits clathrin-mediated endocytosis and causes formation of nonproductive membraneless clathrin cages. reference_section_type: ABSTRACT - id: PMID:20160091 title: Endocytosis and clathrin-uncoating defects at synapses of auxilin knockout mice. reference_review: relevance: HIGH correctness: VERIFIED review_notes: "Cached publication (publications/PMID_20160091.md) PubMed title matches the YAML title exactly; abstract states auxilin acts as a co-chaperone supporting HSC70-dependent clathrin uncoating, and auxilin-knockout synapses accumulate clathrin-coated vesicles/empty cages with impaired endocytosis, directly supporting the clathrin-uncoating and synaptic-vesicle-recycling core functions (cited in core_functions)." findings: - statement: Auxilin and GAK act as co-chaperones supporting HSC70-dependent clathrin uncoating of clathrin-coated vesicles; auxilin-knockout synapses show increased clathrin-coated vesicles/empty cages and impaired synaptic vesicle endocytosis. reference_section_type: ABSTRACT - id: PMID:29735704 title: LRRK2 phosphorylation of auxilin mediates synaptic defects in dopaminergic neurons from patients with Parkinson's disease. findings: - statement: LRRK2 phosphorylates auxilin in its clathrin-binding domain, altering clathrin binding and disrupting synaptic vesicle endocytosis in PD dopaminergic neurons; auxilin interacts with the clathrin heavy chain CLTC. reference_section_type: RESULTS - id: Reactome:R-HSA-421836 title: Clathrin-mediated endocytosis (cytosol localization) findings: [] - id: Reactome:R-HSA-432688 title: Vesicle biogenesis (cytosol localization) findings: [] - id: Reactome:R-HSA-8868658 title: Clathrin-mediated endocytosis (cytosol localization) findings: [] - id: Reactome:R-HSA-8868659 title: Clathrin-mediated endocytosis (cytosol localization) findings: [] - id: Reactome:R-HSA-8868660 title: Clathrin-mediated endocytosis (cytosol localization) findings: [] - id: Reactome:R-HSA-8869438 title: Clathrin-mediated endocytosis (cytosol localization) findings: [] - id: Reactome:R-HSA-8871193 title: Clathrin-mediated endocytosis (cytosol localization) findings: [] - id: Reactome:R-HSA-8871194 title: Clathrin-mediated endocytosis (cytosol localization) findings: [] - id: file:human/DNAJC6/DNAJC6-uniprot.txt title: UniProt entry O75061 (AUXI_HUMAN), auxilin findings: - statement: Auxilin recruits HSPA8/HSC70 to clathrin-coated vesicles and promotes the ATP-dependent dissociation of clathrin from CCVs; binds clathrin cages stoichiometrically; the J domain mediates HSPA8 interaction and is required for basket dissociation; mutations cause PARK19A/PARK19B Parkinson disease. reference_section_type: OTHER core_functions: - description: Clathrin-uncoating co-chaperone that binds the clathrin heavy chain and clathrin cages and, via its J domain, recruits HSPA8/HSC70 and stimulates its ATPase activity to drive ATP-dependent disassembly of the clathrin coat. molecular_function: id: GO:0032050 label: clathrin heavy chain binding locations: - id: GO:0030136 label: clathrin-coated vesicle supported_by: - reference_id: file:human/DNAJC6/DNAJC6-uniprot.txt supporting_text: Interacts with CLTC; this interaction produces a local change in heavy-chain contacts - reference_id: file:human/DNAJC6/DNAJC6-uniprot.txt supporting_text: binds tightly to the clathrin cages, at a - description: HSP70/HSC70 co-chaperone activity, recruiting and stimulating the ATPase of HSPA8/HSC70 through its J domain to power clathrin coat disassembly. molecular_function: id: GO:0031072 label: heat shock protein binding locations: - id: GO:0030136 label: clathrin-coated vesicle supported_by: - reference_id: file:human/DNAJC6/DNAJC6-uniprot.txt supporting_text: Interacts with HSPA8/HSC70 in an ATP-dependent manner; this interaction stimulates the HSPA8's ATPase activity - description: Drives clathrin coat disassembly / synaptic vesicle uncoating during clathrin-mediated endocytosis, supporting synaptic vesicle recycling at nerve terminals. molecular_function: id: GO:0031072 label: heat shock protein binding locations: - id: GO:0098894 label: extrinsic component of presynaptic endocytic zone membrane supported_by: - reference_id: PMID:20160091 supporting_text: act as cochaperones to support the Hsc70-dependent clathrin uncoating of clathrin-coated vesicles directly_involved_in: - id: GO:0072318 label: clathrin coat disassembly proposed_new_terms: [] suggested_questions: - question: 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? - question: 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? - question: To what extent can the ubiquitous homolog GAK compensate for neuronal auxilin loss, and does incomplete compensation explain the dopaminergic-neuron vulnerability in PARK19? suggested_experiments: - description: 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. - description: 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. - description: 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.