Synaptotagmin family member involved in vesicular and membrane trafficking which does not bind Ca(2+) (Probable). Inhibits clathrin-mediated and bulk endocytosis, functions to ensure precision in vesicle retrieval (PubMed:29311685). Plays an important role in dopamine transmission by regulating endocytosis and the vesicle-recycling process (PubMed:29311685). Essential component of a neuronal vesicular trafficking pathway that differs from the synaptic vesicle trafficking pathway but is crucial for development and synaptic plasticity (PubMed:30808661). In macrophages and microglia, inhibits the conventional cytokine secretion, of at least IL6 and TNF, and phagocytosis (PubMed:28686317, PubMed:23303671). In astrocytes, regulates lysosome exocytosis, mechanism required for the repair of injured astrocyte cell membrane (PubMed:26450452). Required for the ATP13A2-mediated regulation of the autophagy-lysosome pathway (PubMed:27278822). Homodimer. Can also form heterodimers. Interacts with PRKN (By similarity). Interacts (via C2 2 domain) with AGO2 and SND1; the interaction with SND1 is direct (PubMed:24882364). Interacts with KIF1A; the interaction increases in presence of calcium (PubMed:30808661). Localized in vesicles that travels in axonal and dendritic shafts in both anterograde and retrograde directions (PubMed:30808661). In macrophages and microglia, recruited in phagosomes at early stages of phagocytosis (PubMed:28686317, PubMed:23303671). Expressed in cerebellun, cerebellar cortex, hippocampus, olfactory bulb and spinal cord (at protein level) (PubMed:30808661). Expressed by neurons, astrocytes and microglia (at protein level) (PubMed:28686317, PubMed:26450452). Expressed in macrophages (at protein level) (PubMed:23303671). Abundant across the brain, expression increases progressively over the first 2 weeks after birth. The second C2 domain/C2B is required for the inhibitory role in both clathrin-mediated and bulk endocytosis. The transmembrane domain and the first C2 domain/C2A are critical for the inhibitory role in clathrin-mediated endocytosis or bulk endocytosis, respectively. Unlike in other synaptotagmin family members, the first C2 domain/C2A does not bind Ca(2+) neither mediates Ca(2+)-dependent phospholipid binding. An aspartate-to-serine substitution in this domain inactivates Ca(2+)/phospho-lipid binding. Ubiquitinated, at least by PRKN, and targeted to the proteasome complex for degradation. Ubiquitination is inhibited by ATP13A2. Knockout is lethal (PubMed:30808661). Conditional knockout mice for dopaminergic neurons show increased dopamine release, accelerated vesicle pools replenishment and enlarged releasable vesicle pools in the striatum (PubMed:29311685). Forebrain-specific conditional knockouts are viable, fertile and have normal life span. They show impaired learning an memory (PubMed:30808661). Belongs to the synaptotagmin family.