The vesicular monoamine transporter 2 (VMAT2; also known as VAT2 and SCL18A) is a 55 - 75 kDa member of the vesicular transporter family, a major facilitator superfamily. VMAT2 is a 12 transmembrane (TM) glycoprotein that is found in the membrane of brain neurosecretory vesicles. It transports monoamines (dopamine, serotonin, and particularly histamine) from the cytosol into secretion vesicles by exchanging two H+ ions for one molecule of amine.
Human VMAT2 is 514 amino acids (aa) in length. It contains a 20 aa and 52 aa N- and C-terminal cytoplasmic domain, plus an extended 88 aa luminal loop between aa 42 - 129. There is one luminal, intrachain disulfide bond that contributes to amine transport (C126 - C333). In addition, residues in TM domains 5 - 8 (aa 220 - 352) and 9 - 12 (aa 358 - 462) also contribute to high affinity ligand interaction. VMAT2 is constitutively phosphorylated by CKII on S511 and S513. Within the cytoplasmic C-terminus, human VMAT2 is 94% aa identical to rat VMAT2.