Growth hormone (GH)-induced tyrosine-phosphorylated proteins in cells that express GH receptors.
We have shown previously that growth hormone (GH)-induced tyrosine phosphorylation of a 95-kDa protein in mouse L-cells stably transfected with the GH receptor. In addition to induction of pp95, we have established that GH also induces tyrosine phosphorylation of a 42-kDa protein and a 130-kDa protein, as detected with phosphotyrosine antibodies. A time course of tyrosine phosphorylation on GH treatment indicates that within the GH signal transduction cascade, tyrosine phosphorylation of pp95 occurs by 1 min, whereas tyrosine phosphorylation of pp42 was not detected until 5 min. Additionally, the concentration of GH needed to stimulate tyrosine phosphorylation of pp42 was greater than that required for pp95. The pp42 protein comigrates with a 42-kDa protein identified as extracellular signal-regulated kinase 2 (ERK2). Growth factors, such as FGF, PDGF, IGF-I, and insulin, induce tyrosine phosphorylation of pp42 in pGHR-W10 cells and in 3T3-F442A preadipocytes; however, they are unable to induce pp95. These results suggest that GH induction of tyrosine-phosphorylated pp42 may represent a common signal transduction point of various growth factors, including GH, whereas tyrosine phosphorylation of pp95 is GH specific.
Harding
P A
PA
Department of Biological Sciences, Ohio University, Athens 45701, USA.
Wang
X Z
XZ
Kopchick
J J
JJ
D017667:Adipocytes; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D013006:Growth Hormone / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D007739:L Cells; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011986:Receptors, Somatotropin / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D013234:Stem Cells
D010750:Phosphoproteins; D011986:Receptors, Somatotropin; D011994:Recombinant Proteins; D013006:Growth Hormone; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1