The transgene contains a single copy of the mouse tyrosinase gene including all five exons, the 5' and 3' untranslated regions (UTRs), and ~155 kb of upstream sequence from which the locus control region (LCR), at -12 kb, has been deleted, leaving the upstream sequence intact. Transgenic mice were generated by IMYT (ICSI-mediated YAC transfer) of the 250-kb yeast artificial chromosome (YAC) YRTdeltaLCR, derived by homologous recombination of the YAC YRT2; YRT2 originated from a YAC library made from strain C3H genomic DNA. Expression of the transgene is demonstrated by its partial rescue of the pigment phenotype of albino mice. (J:211464)