The molecular basis of brown, an old mouse mutation, and of an induced revertant to wild type

Emanuel Zdarsky, Jack Favor, Ian Jackson

Research output: Contribution to journalArticlepeer-review


The murine b locus encodes the tyrosinase related protein, TRP-1, a putative membrane-bound, copper-containing enzyme having about 40% amino acid identity with tyrosinase. The protein is essential for production of black rather than brown hair pigment. We show that skin of mutant brown mice contains the same amount of TRP-1 mRNA as wild type. On sequencing the coding region of the mutant mRNA we find four nucleotide differences from the wild-type (Black) sequence. Two of these differences result in different amino acid residues encoded by the brown allele. By sequencing the TRP-1 gene from a mouse in which a reversion from brown to Black has been induced by ethylnitrosourea we are able to show that only one of these amino acid changes, which substitutes a tyrosine for a conserved cysteine, is the cause of the brown phenotype. This mutation is adjacent to another cysteine at which, in the analogous position in tyrosinase a mutation results in the albino phenotype. The sequence of the revertant is the first report of DNA sequence of an ethylnitrosourea-induced genetic change in mouse.
Original languageEnglish
Pages (from-to)443-9
Number of pages7
Issue number2
Publication statusPublished - Oct 1990


  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Hair Color/genetics
  • Melanocytes/metabolism
  • Membrane Glycoproteins
  • Mice
  • Molecular Sequence Data
  • Mutation
  • Open Reading Frames
  • Oxidoreductases
  • Phenotype
  • Polymerase Chain Reaction
  • Proteins/genetics
  • RNA, Messenger/biosynthesis


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