Himalayan, an allele at the tryosonase locus, arose spontaneously in the offspring of a cross between a DBA/2J male and an AKR/J female at The Jackson Laboratory in 1958. An affected male was backcrosses to an AKR/J female and the Tyrc-h/Tyrc carriers were mated to a C57BL/10Gn. Pairs were mated to produce the Tyrc-h/Tyrc-h mouse. The mutation was backcrossed onto strain C57BL/6J and was cryopreserved in 1987 by mating B6.Cg-Tyrc-h homozygous males at N36F1 to C57BL/6J females.
|Gene Symbol and Name||Tyr, tyrosinase|
|Strain of Origin||(DBA/2 x AKR/J)F1|
|General Note||Melanin granules of the retina are indistinguishable from those of chinchilla or of wild-type homozygotes (J:5001). Pigment synthesis in himalayan mice is temperature-sensitive; pigment develops in growing hairs of mice housed at 15oC but not in those housed at 30oC (J:6275). In explanation of this effect, it has been shown that tyrosinase in these mice is heat-labile (J:12173), being maximally active at well below body temperature. Tyrosinase of Tyrch homozygotes is strongly bound by an inhibitor at 37oC but not at lower temperatures (J:6508).|
|Molecular Note||The mutation in the himalayan allele was found to be an A-to-G point mutation at coding nucleotide 1259 that results in an amino acid change at position 420 from histidine to arginine (p.H420R).|