GTP binding proteins and growth factor signal transduction.
There is a large body of evidence supporting a role for GTP-binding proteins in signal transduction by growth factors. In certain cells, ligands which activate or inhibit the production of cAMP via heterotrimeric G proteins promote replication of the target cell. These mechanisms play an important role in a limited number of tumours. Ligands which activate PI hydrolysis through heterotrimeric G proteins may also promote growth in certain systems, but the precise role for PI hydrolysis remains to be determined. Receptors with intrinsic tyrosine kinases may also interact with the heterotrimeric G proteins, but it is not known if these interactions represent side reactions, or whether they are central in the responses of certain cell types. Lastly, p21ras and other small molecular weight G proteins appear to be profoundly important in growth control. The tyrosine kinase growth factor receptors may interact indirectly with these GTP binding proteins via GAP proteins. The molecular detail of this process is emerging rapidly and is likely to be worked out in the near future.
Ives
H E
HE
Department of Medicine, University of California, San Francisco 94143.
D000818:Animals; D002455:Cell Division / Q000502:physiology*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006133:Growth Substances / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism; D015398:Signal Transduction
D006133:Growth Substances; D010716:Phosphatidylinositols; D011505:Protein-Tyrosine Kinases; D019204:GTP-Binding Proteins; D016283:Proto-Oncogene Proteins p21(ras)