Ca+2-dependent secretion activator 1 (Ca+2-dependent activator protein for secretion 1, CAPS-1, CADPS, CAPS, CAPS1, KIAA1121)

Function: 1) Ca⁺²-binding protein 2) role in exocytosis of vesicles containing neurotransmitters & neuropeptides 3) probably acts upstream of fusion in the biogenesis or maintenance of mature secretory vesicles 4) preferentially binds to dense-core vesicles (DCV) but not to small clear synaptic vesicles 5) binds phosphoinosides, with a strong selectivity for PIP2 over PIP3 6) may specifically mediate the Ca⁺²-dependent exocytosis of large dense-core vesicles as PIP2-binding protein - acts at prefusion step following ATP-dependent priming - role in dense-core vesicle membrane fusion 7) role in small clear synaptic vesicles exocytosis 8) unclear whether function related to Ca⁺² triggering 9) regulates catecholamine loading of dense-core vesicles 10) interacts with the dopamine receptor DRD2 Structure: - homodimer - contains 1 C2 domain - contains 1 MHD1 domain (MUNC13 homology domain 1) - contains 1 PH domain - essential for regulated exocytosis binds phospholipids & plasma membrane Compartment: - cytoplasmic vesicle, membrane-associated - strongly enriched in synaptic fractions - probably localizes to different vesicles than CADPS2 Alternative splicing: named isoforms=5 Expression: - specifically expressed in neural & endocrine secretory tissues - expressed in brain & pancreas > heart - expressed in fetal heart, cerebellum, cerebral cortex, medulla oblongata, occipital pole, frontal & temporal lobes, putamen - weak expression in spinal cord

Properties

SIZE: MW = 153 kD entity length = 1353 aa COMPARTMENT: cytoplasm MOTIF: C2 domain {400-481} MOTIF: binding site FOR-BINDING-OF: phospholipid Ca+2-binding site PH domain {521-624} DRD2 interaction {790-1129} MOTIF: MHD1 {931-1111} DCV interaction {1177-1353}

Database Correlations

OMIM 604667 UniProt Q9ULU8 PFAM correlations

References

UniProt :accession Q9ULU8