ASSIGNMENT OF THE BETA-B1 CRYSTALLIN GENE (CRYBB1) TO HUMAN-CHROMOSOME-22 AND MOUSE CHROMOSOME-5

By using primers complementary to the rat beta B1 crystallin gene sequ ence, we amplified exons 5 and 6 of the orthologous human gene (CRYBB1 ). The amplified human segments displayed greater than 88% sequence ho mology to the corresponding rat and bovine sequences. CRYBB1 was assig ned to the group 5 region in 22q11.2-q12.1 by hybridizing the exon 6 P CR product to somatic cell hybrids containing defined portions of huma n chromosome 22. The exon 5 and exon 6 PCR products of CRYBB1 were use d to localize, by interspecific backcross mapping, the mouse gene (Cry bb1) to the central portion of chromosome 5. Three other beta crystall in genes (beta B2(-1), beta B3, and beta A4) have previously been mapp ed to the same regions in human and mouse. We demonstrate that the bet a B1 and beta A4 crystallin genes are very closely linked in the two s pecies. These assignments complete the mapping and identification of t he human and mouse homologues of the major beta crystallins genes that are expressed in the bovine lens. (C) 1995 Academic Press, Inc.