The related genes encoding growth hormone and prolactin have been dispersed to chromosomes 10 and 17 in the rat.

We have assigned the rat GH gene to chromosome 10 and the rat PRL gene to chromosome 17. DNA from a series of mouse BWTG3 x rat hepatocyte somatic cell hybrids, each of which has retained a unique complement of rat chromosomes, was analyzed for the presence of rat GH and PRL genomic fragments by Southern blotting. Radiolabeled complementary DNAs (cDNAs) encoding rat GH and rat PRL were used as molecular probes. Based upon these assignments, we conclude that the evolutionarily related GH and PRL genes have been dispersed to different chromosomes in rat as in man.