Identification of Novel ras Family Genes in A Human Teratocarcinoma Cell Line by Oligonucleotide Screening

Guanine nucleotide-binding and hydrolyzing proteins have been the subject of intense investigation in recent years. We now recognize their fundamental importance in normal and aberrant cellular physiology, and the diversity of functions that they have assumed in eukaryotic cells. These regulatory proteins all share a common mechanism based on the nature of the bound nucleotide and the rates of nucleotide hydrolysis and exchange. When bound to GTP these proteins interact with one set of cellular components, yet interact with another set in their GDP-bound forms. In most cases, the release of GDP is slow and is catalyzed by other protein factors. Certain classes of GTPases with slow intrinsic rates of hydrolysis also interact with catalyzing cofactors which greatly accelerate their return to a conformationally “inactive” form. Eukaryotic cells have repeatedly employed this switching mechanism to regulate such diverse cellular functions as protein synthesis, vesicle targeting, signal transduction, cellular proliferation, and differentiation. ^{1 - 4}