Metazoan Synaptic vesicle glycoprotein 2 (SV2) and related small molecule transporters of the Major Facilitator Superfamily
This family is composed of metazoan synaptic vesicle glycoprotein 2 (SV2) and related small molecule transporters including those that transport inorganic phosphate (Pht), aromatic compounds (PcaK and related proteins), proline/betaine (ProP), alpha-ketoglutarate (KgtP), citrate (CitA), shikimate (ShiA), and cis,cis-muconate (MucK), among others. SV2 is a transporter-like protein that serves as the receptor for botulinum neurotoxin A (BoNT/A), one of seven neurotoxins produced by the bacterium Clostridium botulinum. BoNT/A blocks neurotransmitter release by cleaving synaptosome-associated protein of 25 kD (SNAP-25) within presynaptic nerve terminals. Also included in this family is synaptic vesicle 2 (SV2)-related protein (SVOP) and similar proteins. SVOP is a transporter-like nucleotide binding protein that localizes to neurotransmitter-containing vesicles. The SV2-like family belongs to the Major Facilitator Superfamily (MFS) of membrane transport proteins, which are thought to function through a single substrate binding site, alternating-access mechanism involving a rocker-switch type of movement.
Feature 1:putative chemical substrate binding pocket [chemical binding site]
Evidence:
Comment:based on the structures of MFS transporters with bound substrates, substrate analogs, and/or inhibitors
Comment:since MFS proteins facilitate the transport of many different substrates including ions, sugar phosphates, drugs, neurotransmitters, nucleosides, amino acids, and peptides, the residues involved in substrate binding may not be strictly conserved among superfamily members
Comment:the substrate binding site or translocation pore has access to both sides of the membrane in an alternating fashion through a conformational change of the MFS transporter
Jiyao W et al.(2023). "The conserved domain database in 2023.",