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Permease P (pink-eyed dilution). Mutations in the human melanosomal P gene were responsible for classic phenotype of oculocutaneous albinism type 2 (OCA2). Although the precise function of the P protein is unknown, it was predicted to regulate the intraorganelle pH, together with the ATP-driven proton pump. It shows significant sequence similarity to the Na+/H+ antiporter NhaD from Vibrio parahaemolyticus. Both proteins belong to ArsB/NhaD superfamily of permeases that translocate sodium, arsenate, sulfate, and organic anions across biological membranes in all three kingdoms of life. A typical ArsB/NhaD permease contains 8-13 transmembrane domains.
Jiyao W et al.(2023). "The conserved domain database in 2023.",