| Modification Notes |
The superfamily of GTP binding proteins, for which the Ras proteins are prototypes, has been implicated in regulation of a broad range of biological activities . One member of the family, Cdc42Hs (originally referred to as Gp or G25K), appears to represent the human homolog of the Saccharomyces cerevisiae cell division protein, Cdc42Sc. The predicted amino acid sequence of Cdc42Hs is very similar to those of various members of the Ras superfamily proteins including N-, K- and H-Ras proteins (30-35% identical), Rho proteins (50% identical) and the Rac proteins (70% identical). A second S. cerevisiae protein, Cdc24, which is known from complementation studies to act with Cdc42Sc to regulate the development of normal cell shape in yeast, contains a region of sequence homology with the Dbl oncogene product. Dbl specifically catalyzes the dissociation of GDP from Cdc42Hs, thus representing a highly selective guanine nucleotide exchange factor for Cdc42Hs. |