Human genome contains four genes homologous to transforming genes of Harvey and Kirsten murine sarcoma viruses

Abstract

Harvey and Kirsten murine sarcoma viruses each encode a structurally and functionally related 21-kilodalton protein (p21), which is the transforming protein of each virus. Using probes from the 0.9-kilobase (kb) p21-coding region of each virus (called v-Ha-ras and v-Ki-ras, respectively), we have molecularly cloned from normal human genomic DNA the sequences that hybridize to these probes. Four evolutionarily divergent restriction endonuclease fragments were isolated. Two hybridized preferentially to v-Ha-ras and were designated human c-Ha-ras1 and c-Ha-ras2; two hybridized preferentially to v-Ki-ras and were called c-Ki-ras1 and c-Ki-ras2. Human c-Ha-ras1 contained 0.9 kb of sequence homologous with v-Ha-ras interspersed with three intervening sequences; this gene was closely related to a previously cloned rat c-Ha-ras gene that also contained intervening sequences. Human c-Ha-ras2 was more divergent from v-Ha-ras and also hybridized poorly to human c-Ha-ras1. One c-Ki-ras gene contained 0.9 kb homologous to v-Ki-ras and had one intervening sequence, whereas the other contained only 0.3 kb homologous to v-Ki-ras. The results indicated that human DNA contains several copies of the c-ras family and that c-Ha-ras1 (with intervening sequences) was more highly conserved evolutionarily than was c-Ha-ras2.