V-type proton ATPase subunit B, brain isoform is an enzyme that in humans is encoded by the ATP6V1B2gene.
This gene encodes a component of vacuolar ATPase (V-ATPase), a multisubunit enzyme that mediates acidification of eukaryotic intracellular organelles. V-ATPase dependent organelle acidification is necessary for such intracellular processes as protein sorting, zymogen activation, receptor-mediated endocytosis, and synaptic vesicle proton gradient generation. V-ATPase is composed of a cytosolic V1 domain and a transmembrane V0 domain. The V1 domain consists of three A, three B, and two G subunits, as well as a C, D, E, F, and H subunit. The V1 domain contains the ATP catalytic site. The protein encoded by this gene is one of two V1 domain B subunit isoforms and is the only B isoform highly expressed in osteoclasts.
In melanocytic cells ATP6V1B2 gene expression may be regulated by MITF.
^Bernasconi P, Rausch T, Struve I, Morgan L, Taiz L (Nov 1990). "An mRNA from human brain encodes an isoform of the B subunit of the vacuolar H(+)-ATPase". J Biol Chem. 265 (29): 17428–31. PMID2145275.