Vacuolar ATPase assembly factor VMA12 (VMA12)

Vacuolar ATPase assembly factor VMA12 (VMA12) is a transmembrane protein located in the endoplasmic reticulum (ER) that acts as a dedicated assembly factor (chaperone) for the membrane-embedded V0 sector of the vacuolar-type H+-ATPase (V-ATPase) proton pump. It participates in the recruitment and stabilization of V-ATPase membrane subunits during assembly, interacting with Vma22 and subunits a, e, and f to promote proper V-ATPase formation[1][3]. VMA12 is not part of the mature V-ATPase proton pump complex itself, but is essential for its biogenesis and quality control, ensuring only properly assembled complexes are exported from the ER. Mutations in the human orthologs (including TMEM199) result in congenital disorders of glycosylation and liver disease, as well as defects in endolysosomal acidification[1]. VMA12 is not a therapeutic target per se, and no known drugs directly target this assembly factor.

Other names

VMA12Vacuolar ATPase assembly protein VMA12C17orf32TMEM199VPH2MGC45714Transmembrane protein 199CDG2P