Glucagon and p21 ras enhance the phosphorylation of the same 38-kilodalton membrane protein from rat liver cells.
We had reported earlier the enhanced phosphorylation of a 38-kilodalton protein (p38) in rat liver plasma membrane by ras proteins. Now we show that glucagon increased the phosphorylation of the same protein. The nature and site(s) of phosphorylation were the same as those for the ras proteins. Both ATP and GTP could donate phosphate for the phosphorylation of p38. The stimulation of p38 phosphorylation by glucagon was guanine nucleotide dependent. This observation, together with our data on the stimulation of p38 phosphorylation by AIF4-, suggest the involvement of G proteins in the reaction. We also showed that glucagon stimulates the phosphorylation of p38 in vivo.
Centre for Cellular and Molecular Biology, Hyderabad, India.
A N
AN
Hegde
M R
MR
Das
D000818:Animals; D004591:Electrophoresis, Polyacrylamide Gel; D005934:Glucagon / Q000494:pharmacology*; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D008970:Molecular Weight; D015689:Oncogene Protein p21(ras) / Q000494:pharmacology*; D010449:Peptide Mapping; D010750:Phosphoproteins / Q000302:isolation & purification; D010766:Phosphorylation; D051381:Rats; D011919:Rats, Inbred Strains; D011994:Recombinant Proteins / Q000494:pharmacology
D008565:Membrane Proteins; D010750:Phosphoproteins; D011994:Recombinant Proteins; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D005934:Glucagon; D015689:Oncogene Protein p21(ras)