Biological properties of human c-Ha- ras 1 genes mutated at codon 12

Vertebrate genomes contain proto-oncogenes whose enhanced expression or alteration by mutation seems to be involved in the development of naturally occurring tumours. These activated genes, usually assayed by their ability to induce the malignant transformation of NIH 3T3 cells, are frequently related to the ras oncogene of Harvey (Ha-ras) or Kirsten (Ki-ras) murine sarcoma viruses, or a third member of this family (N-ras). Activation involves point mutation whic h often affect codon 12 (refs 16-26) of the encoded 21,000-molecular weight polypeptide (p21). To provide insight into structural requirements involved in p21 activation, the authors have now constructed 20 mutant c-Ha-ras 1 genes by in vitro mutagenesis, each encoding a different amino acid at codon 12.