Mapping the human CAS2 gene, the homologue of the mouse brown (b) locus, to human chromosome 9p22-pter.
Melanin biosynthesis is a multistep process with the first step being the conversion of L-tyrosine to L-Dopa catalyzed by the enzyme tyrosinase. The enzymes which catalyze the other steps of melanogenesis are not known. One murine pigmentation gene, the brown (b) locus, when mutated, leads to a brown or hypopigmented coat. The b-locus protein has been shown to display catalase activity. The human b-locus, therefore, is designated as CAS2. We used the mouse b-locus cDNA to isolate the human homologue, which in turn, was used to map the CAS2 locus to a human chromosome. The potential CAS2 protein codes for 527 amino acids containing a putative signal sequence and transmembrane domain. The CAS2 protein has primary and probably secondary structures similar to human tyrosinase. The CAS2 was mapped to human Chromosome 9 by somatic cell hybridization and, more specifically, to 9p22-pter by in situ hybridization. The assignment of CAS2 on the human Chromosome 9 extends this region of known homology on mouse Chromosome 4.
Chintamaneni
C D
CD
Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis 46202-5120.
Ramsay
M
M
Colman
M A
MA
Fox
M F
MF
Pickard
R T
RT
Kwon
B S
BS
D000595:Amino Acid Sequence; D000818:Animals; D015139:Blotting, Southern; D002871:Chromosome Banding; D002874:Chromosome Mapping; D002899:Chromosomes, Human, Pair 9; D003001:Cloning, Molecular; D006224:Cricetinae; D003412:Cricetulus; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D005796:Genes; D006801:Humans; D006822:Hybrid Cells / Q000201:enzymology; D051379:Mice; D008969:Molecular Sequence Data; D014442:Monophenol Monooxygenase / Q000235:genetics*; D009693:Nucleic Acid Hybridization; D012689:Sequence Homology, Nucleic Acid
D004247:DNA; D014442:Monophenol Monooxygenase