Plays a role in the control of regulated secretion in neural and endocrine cells, enhancing selectively low-frequency neurotransmission. Positively regulates vesicle fusion by maintaining the readily releasable pool of secretory vesicles. (Microbial infection) Receptor for C.botulinum neurotoxin type A (BoNT/A, botA); the toxin binds Sv2c via extracellular loop 4 (PubMed:16543415). Restores uptake of BoNT/A in rat cells that are deleted for SV2 receptor (PubMed:16543415, PubMed:18815274). (Microbial infection) Possible receptor for C.botulinum neurotoxin type D (BoNT/D, botD); BoNT/D does not bind to extracellular loop 4 as do BoNT/A and BoNT/E (PubMed:21483489). Another group does not find a convincing interaction with SV2 (PubMed:21632541). (Microbial infection) Receptor for C.botulinum neurotoxin type F (BoNT/F); binding requires glycosylation of Asn-573 (PubMed:19476346, PubMed:19650874). Interacts with SYT1 in a calcium-dependent manner. (Microbial infection) Interacts with C.botulinum neurotoxin type A (BoNT/A, botA). (Microbial infection) Interacts with C.botulinum neurotoxin type F (BoNT/F) (PubMed:19650874). Interaction requires glycosylation of SV2 proteins (PubMed:19476346, PubMed:19650874). Enriched in small synaptic vesicles and adrenal microsomes, not present in chromaffin granules. Associated with both insulin granules and synaptic-like microvesicles in insulin-secreting cells of the pancreas. Expressed at high levels in very few brain areas including the striatum, midbrain and hindbrain, and in the olfactory bulb. Expressed at lower levels in cerebrum, hippocampus and cerebellum (at protein level). Mainly expressed in brain; also detected in lung, liver, kidney. N-glycosylated. Belongs to the major facilitator superfamily. The use of this protein as a coreceptor for C.botulinum type D (BoNT/D, botD) is controversial. In double SV2A/SV2B knockout mice BoNT/D does not degrade its synaptobrevin target; introducing SV2A, SV2B or SV2C restores target cleavage (PubMed:21483489). However another group does not find a convincing interaction with SV2 (PubMed:21632541).