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Rosemblat S , Durhampierre D , Gardner JM , Nakatsu Y , Brilliant MH , Orlow SJ
Identification of a Melanosomal Membrane-Protein Encoded by the Pink-Eyed Dilution (Type-Ii Oculocutaneous Albinism) Gene
Proceedings of the National Academy of Sciences of the United States of America. 1994 Dec 6;91(25) :12071-12075
AbstractThe pink-eyed dilution (p) locus in the mouse is critical to melanogenesis; mutations in the homologous locus in humans, P, are a cause of type II oculocutaneous albinism. Although a cDNA encoded by the p gene has recently been identified, nothing is known about the protein product of this gene. To characterize the protein encoded by the p gene, we performed immunoblot analysis of extracts of melanocytes cultured from wild-type mice with an antiserum from rabbits immunized with a peptide corresponding to amino acids 285-298 of the predicted protein product of the murine p gene. This antiserum recognized a 110- kDa protein. The protein was absent from extracts of melanocytes cultured from mice with two mutations (p(cp) and p) in which transcripts of the p gene are absent or greatly reduced. Introduction of the cDNA for the p gene into p(cp) melanocytes by electroporation resulted in expression of the 3.3-kb mRNA and the 110-kDa protein. Upon subcellular fractionation of cultured melanocytes, the 110-kDa protein was found to be present in melanosomes but absent from the vesicular fraction; phase separation performed with the nonionic detergent Triton X-114 confirmed the predicted hydrophobic nature of the protein. These results demonstrate that the p gene encodes a 110-kDa integral melanosomal membrane protein and establish a framework by which mutations at this locus, which diminish pigmentation, can be analyzed at the cellular and biochemical levels.
NotesEnglish Article PW708 PROC NAT ACAD SCI USA