Assignment of three rat cellular RAS oncogenes to chromosomes 1, 4, and X.

Mouse hepatoma-rat hepatocyte hybrids that segregate rat chromosomes were used to determine the chromosomal localization of rat cellular RAS genes. The cellular KRAS gene, homologous to the Kirsten sarcoma virus oncogene was mapped to rat chromosome 4, a chromosome that is often present in three copies in rat neurogenic tumor cells and transformed glial cells. The rat cellular HRAS-1 gene, homologous to the Harvey sarcoma virus oncogene was assigned to chromosome 1, whereas its intron-less counterpart HRAS-2 was mapped to the X chromosome. Since the human HRAS-2 also resides on the X chromosome, it appears that the cellular HRAS-2 gene (or pseudogene) conserved its chromosomal localization during mammalian evolution.