Ca+2-dependent secretion activator 2 (Ca+2-dependent activator protein for secretion 2, CAPS-2, CADPS2, CAPS2, KIAA1591)
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Function
- Ca+2-binding protein
- role in exocytosis of vesicles filled with neurotransmitters & neuropeptides
- probably acts upstream of fusion in the biogenesis or maintenance of mature secretory vesicles
- regulates neurotrophin release from granule cells, thus role in cell differentiation & survival during cerebellar development
- may specifically mediate the Ca+2-dependent exocytosis of large dense-core vesicles & other dense-core vesicles
- interacts with the dopamine receptor DRD2
- isoform 2 is phosphorylated upon DNA damage, probably by ATM or ATR
Structure
- homodimer
- contains 1 C2 domain
- contains 1 MHD1 domain (MUNC13 homology domain 1 domain)
- contains 1 PH domain with role in regulation of exocytosis, binds phospholipids
Compartment
- cytoplasmic vesicle membrane
- enriched in synaptic fractions
- probably localizes to different vesicles compared to CADPS
- enriched on vesicular structures in the parallel fiber terminal of granule cells that are distinct from synaptic vesicles
Alternative splicing
named isoforms=3
Expression
- widely expressed
- expressed in all adult & fetal tissues examined
- strongest expression in kidney & pancreas
- in CNS, expressed in cerebellum > cerebral cortex, occipital pole, frontal & temporal lobes > medulla, spinal cord, putamen