Calcium-binding protein involved in exocytosis of vesicles filled with neurotransmitters and neuropeptides. Probably acts upstream of fusion in the biogenesis or maintenance of mature secretory vesicles. Regulates neurotrophin release from granule cells leading to regulate cell differentiation and survival during cerebellar development. May specifically mediate the Ca(2+)-dependent exocytosis of large dense-core vesicles (DCVs) and other dense-core vesicles. Homodimer. Interacts with the dopamine receptor DRD2 (By similarity). Membrane-associated to vesicles. Strongly 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. Highly expressed in cerebellum. Also expressed in non-neuronal tissues such as lung, spleen, testis, uterus and ovary. Highly expressed in brain. In brain, it is highly expressed in cerebellum, cortex, olfactory bulb, CA1/CA2 regions of the hippocampus, and dentate gyrus, and weakly or not expressed in the CA3 regions of the hippocampus, striatum, thalamus, superior and inferior colliculi, and brain stem. Not present in adult adrenal glands. Isoform 4, but not isoform 3, is highly expressed in postnatal and adult stages of cerebellum. Expressed at stable level during brain development, with a higher level in embryonic brain. The PH domain is essential for regulated exocytosis and binds phospholipids.