Mammalian and Yeast ras Gene Products: Biological Function in Their Heterologous Systems

Abstract
Activated versions of ras genes have been found in various types of malignant tumors. The normal versions of these genes are found in organisms as diverse as mammals and yeasts. Yeast cells that lack their functional ras genes, RAS SC -1 and RAS SC -2, are ordinarily nonviable. They have now been shown to remain viable if they carry a mammalian ras H gene. In addition, yeast-mammalian hybrid genes and a deletion mutant yeast RAS SC -1 gene were shown to induce morphologic transformation of mouse NIH 3T3 cells when the genes had a point mutation analogous to one that increases the transforming activity of mammalian ras genes. The results establish the functional relevance of the yeast system to the genetics and biochemistry of cellular transformation induced by mammalian ras genes.