NUCLEOTIDE SEQUENCE OF EXON I OF THE RAT C-K-RAS GENE

We have isolated a DNA fragment containing exon I of rat cellular proto-oncogene of K-ras and sequenced the exon I. The obtained sequence was compared with that of the corresponding region in viral oncogene of Kirsten strain of murine sarcoma virus (Ki-MSV). The results showed that the exon I sequences of cellular K -ras genes in rat and human cells could encode the same amino acid sequence, while the viral K -ras gene could code for two different amino acids corresponding to the 12th and 37th positions from the N-terminus of K -ras gene product. The amino acid substitutions found between viral and cellular K- ras genes are discussed in relation to the transforming ability of Ki-MSV