Coupling of ras to the T Cell Antigen Receptor
The ras proto-oncogenes, Ha-, Ki- and N-ras, encode 21-kDa GTPases that are critical regulatory proteins in all eukaryotic cells. In most mammalian cell types, ras proteins are essential for cell growth and when constitutively activated by point mutation cause cellular transformation. In some cell types ras proteins have been implicated in differentiation pathways. Their activity is normally regulated by a cycle of binding GTP to give the biologically active form of the protein followed by hydrolysis of bound GTP to GDP. The GDP bound form of the protein is inactive: it is reactivated by exchange of bound GDP for free cytosolic GTP (see other chapters in this volume).
KeywordsHydrolysis Tyrosine Serine Saccharomyces Threonine
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- Heidaran MA, Molloy CJ, Pangelinan M, Choudhury GG, Wang L-M, Fleming TP, Sakaguchi AY, Pierce JH (1992) Activation of the colony-stimulating factor 1 receptor leads to the rapid tyrosine phosphorylation of GTPase-activating protein and activation of cellular p21ras. Oncogene 7:147–152PubMedGoogle Scholar
- Izquierdo M, Downward J, Graves JD, Cantrell DA (1992) The role of protein kinase C in T cell antigen receptor regulation of p21ras: evidence that two ras regulatory pathways co-exist in T cells. Mol Cell Biol 12:(in press)Google Scholar
- Kaibuchi K, Mizuno T, Fujioka H, Yamamoto T, Kishi K, Fukumoto Y, Hori Y, Takai Y (1991) Molecular cloning of the cDNA for stimulatory GDP/GTP exchange protein for smg p21s (ras p21-like small GTP bindng proteins) and characterisation of stimulatory GDP/GTP exchange protein. Mol Cell Biol 11:2873–2880PubMedGoogle Scholar
- Martegani E, Vanoni M, Zippel R, Coccetti P, Brambilla R, Ferrari C, Sturani E, Alberghina L (1992) Cloning by functional complementation of a mouse cDNA encoding a homologue of CDC25, a saccharomyces cerevisiae ras activator. EMBO J 6:2151–2157Google Scholar
- Rayter SI, Woodrow M, Cantrell DA, Downward J (1992) p21ras mediates control of IL2 gene promoter function in T cell activation (submitted)Google Scholar