Molecular mechanisms governing melanogenesis in hamster melanomas: relative abundance of tyrosinase and catalase-B (gp 75).
Variants of the Bomirski family of hamster melanomas whose proliferative rates differ inversely with the genetically determined degree of melanogenesis were probed for two proteins critical in melanogenesis: tyrosinase and catalase-B (gp 75). The parental black tumor Ma contained both proteins in abundance. The amelanotic variant Ab, inducible in culture with L-tyrosine or L-dopa to form melanosomes and to melanize, had minimal tyrosinase, despite high levels of (tyr)mRNA, and no gp 75. Variant MI, hypomelanotic despite abundant tyrosinase, and synthesizing predominantingly pheo-(red) melanin, expressed barely detectable gp 75. These findings suggest a regulatory control of melanogenesis distal to (tyr)mRNA and strengthen the hypothesis that in vivo tyrosinase without catalase-B favors pheo- over eumelanogenesis.
Slominski
A
A
Department of Microbiology and Immunology, Albany Medical College, NY 12208.
Costantino
R
R
Howe
J
J
Moellmann
G
G
D000818:Animals; D002374:Catalase / Q000302:isolation & purification / Q000378:metabolism*; D006224:Cricetinae; D004591:Electrophoresis, Polyacrylamide Gel; D015151:Immunoblotting; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism*; D008543:Melanins / Q000096:biosynthesis*; D008546:Melanoma, Experimental / Q000201:enzymology / Q000473:pathology*; D008647:Mesocricetus; D008970:Molecular Weight; D014442:Monophenol Monooxygenase / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000302:isolation & purification; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
D007527:Isoenzymes; D008543:Melanins; D012333:RNA, Messenger; D002374:Catalase; D014446:Tyrosine 3-Monooxygenase; D014442:Monophenol Monooxygenase