Interaction of ras p21 Proteins with GTPase Activating Protein

ras genes are expressed in all types of eukaryotic cells, and the products of these genes are thought to be involved in the regulation of cell growth (for review, see Barbacid 1987). The products of mammalian ras genes are referred to as p21 proteins: These proteins bind GDP and GTP with high affinity and possess a low intrinsic GTPase activity. Point mutations within the guanine-nucleotide-binding site can activate the biological activity of ras proteins, enabling them to contribute to the process of malignant transformation. The mechanisms by which these mutations cause oncogenic activation are discussed below.