All six rat gamma-crystallin genes are located on chromosome 9

The rat genome contains six genes for the lens-specific gamma-crystallins. Five of these genes are clustered; the location of the sixth gene is not known. To determine whether the sixth gene is located on the same chromosome as the gamma-crystallin gene cluster, a panel of mouse-rat hybrid cell lines, segregating rat chromosomes, was screened for the presence of gamma-crystallin sequences. We show here that the hybrid cell lines contain either all rat gamma-crystallin genes or none, indicating that all six genes map to the same chromosome. The presence of rat gamma-crystallin sequences in the hybrid cell lines was concordant only with the presence of rat chromosome 9, which therefore contains the rat gamma-crystallin genes.