Biosynthesis and intracellular movement of the melanosomal membrane glycoprotein gp75, the human b (brown) locus product
- Memorial Sloan-Kettering Cancer Center, New York, NY (United States) Cornell Univ., New York, NY (United States)
A 75-kDa melanosomal glycoprotein (gp75) is the product of a gene that maps to the b (brown) locus, a genetic locus that determines coat color in the mouse. The b locus is conserved (88% identity) between mouse and human. The mouse monoclonal antibody TA99 was used to study the biosynthesis and processing of gp75. gp75 was synthesized as a 55-kDa polypeptide, glycosylated by addition and processing of five or more Asn-linked carbohydrate chains through the cis and trans Golgi, and transported to melanosomes as a mature 75-kDa form. Synthesis and processing of gp75 was rapid (T{sub 1/2} < 30 min), and early steps in processing were required for efficient export of gp75 was quite stable in the melanosome. Studies with inhibitors of steps in oligosaccharide processing showed that alternative forms of gp75 were generated during trimming reactions by mannosidase IA/IB and that further maturation resulted in the two mature forms of gp75. The authors purpose that the kinetics of biosynthesis and processing reflect events in the biogenesis and maturation of melanosomes.
- OSTI ID:
- 5312640
- Journal Information:
- Experimental Cell Research; (United States), Vol. 196:2; ISSN 0014-4827
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
EPITHELIUM
BIOCHEMISTRY
MEMBRANE PROTEINS
BIOSYNTHESIS
BIOCHEMICAL REACTION KINETICS
CELL CONSTITUENTS
GENES
GLYCOPROTEINS
MAN
MELANIN
MEMBRANE TRANSPORT
TYROSINASE
ANIMAL TISSUES
ANIMALS
BODY
CHEMISTRY
ENZYMES
HYDROXY COMPOUNDS
HYDROXYLASES
KINETICS
MAMMALS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDOREDUCTASES
PIGMENTS
PRIMATES
PROTEINS
REACTION KINETICS
SYNTHESIS
TISSUES
VERTEBRATES
550200* - Biochemistry