The role of ras proteins in insulin signal transduction.
Ras-proteins are guanine nucleotide binding proteins, which, in the GTP bound state emit a strong mitogenic signal. In the GDP bound state, the protein appears inactive. We have found that stimulation by insulin of cells expressing elevated levels of insulin receptors results in a rapid conversion of Ras-GDP into Ras-GTP. This process is part of the signalling pathway leading to immediate-early gene expression and a mitogenic response. There seems to be no involvement of Ras-GTP formation in the process of insulin stimulated glucose transport. Though the precise mechanism by which Ras is converted to the GTP bound state remains to be established, a tight correlation exists between receptor autophosphorylation and Ras-GTP formation.
Maassen
J A
JA
Department of Medical Biochemistry, Sylvius Laboratory, Leiden, The Netherlands.
Burgering
B M
BM
Medema
R H
RH
Osterop
A P
AP
van der Zon
G C
GC
Möller
W
W
Bos
J L
JL
D000818:Animals; D011905:Genes, ras / Q000502:physiology*; D006801:Humans; D007328:Insulin / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*
D007328:Insulin