Probably plays a role in the control of regulated secretion in neural and endocrine cells. (Microbial infection) Receptor for C.botulinum neurotoxin type A (BoNT/A, botA); the toxin binds via extracellular loop 4 (PubMed:16543415). Restores uptake of BoNT/A in mouse and rat cells that are deleted for SV2 receptor (PubMed:16543415, PubMed:18815274). Glycosylation of SV2B is not essential for receptor activity, but enhances the interaction (PubMed:18815274, PubMed:19650874). Also serves as a receptor for the closely related C.botulinum neurotoxin type A2; glycosylation is not essential but enhances the interaction (PubMed:29649119). (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 E (BoNT/E); the toxin probably binds via extracellular loop 4 (PubMed:18815274). Restores uptake of BoNT/E in mouse cells that are deleted for SV2 receptor (PubMed:18815274). Glycosylation of SV2B is not essential for receptor activity, but enhances the interaction (PubMed:19650874). (Microbial infection) Receptor for C.botulinum neurotoxin type F (BoNT/F); binding requires glycosylation of this protein (PubMed:19476346, PubMed:19650874). Interacts with SYT1 in a calcium-independent manner. Forms a complex with SYT1, syntaxin-1 and SNAP25 (By similarity). (Microbial infection) Interacts with C.botulinum neurotoxin type A1 and type A2 (BoNT/A, botA) (PubMed:16543415, PubMed:21632541, PubMed:21483489). Interaction is improved by glycosylation of SV2 (PubMed:29649119). (Microbial infection) Interacts with C.botulinum neurotoxin type D (BoNT/D, botD). (Microbial infection) Interacts with C.botulinum neurotoxin type E (BoNT/E) (PubMed:18815274, PubMed:19476346, PubMed:19650874). Interaction requires glycosylation of SV2 proteins (PubMed:19476346). (Microbial infection) Interacts with C.botulinum neurotoxin type F (BoNT/F) (PubMed:19650874). Interaction requires glycosylation of SV2 proteins (PubMed:19650874). Associated with synaptic-like microvesicles but not with insulin-containing vesicles in insulin-secreting cells of the pancreas (PubMed:16306227). Localizes to microvesicles in the pinealocytes. Localizes to the acrosome in spermatids (PubMed:12754292). Widely expressed throughout the brain. Specifically expressed by pinealocytes in the pineal gland. Also detected in testis (at protein level). Specifically expressed in neural tissues. Expressed in the spinal cord and in all brain regions with a stronger expression in hippocampus and cortex. By amyloid beta peptide. N-glycosylated. The N-terminal cytoplasmic domain is phosphorylated by CK1. 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).