The Fyn tyrosine kinase binds Irs-1 and forms a distinct signaling complex during insulin stimulation.
Irs-proteins link the receptors for insulin/IGF-1, growth hormones, and several interleukins and interferons to signaling proteins that contain Src homology-2 (SH2). To identify new Irs-1-binding proteins, we screened a mouse embryo expression library with recombinant [32P]Irs-1, which revealed a specific association between p59fyn and Irs-1. The SH2 domain in p59fyn bound to phosphorylated Tyr895 and Tyr1172, which are located in YXX(L/I) motifs. Mutation of p59fyn at the COOH-terminal tyrosine phosphorylation site (Tyr531) enhanced its binding to Irs-1 during insulin stimulation. Binding experiments with various SH2 protein revealed that Grb-2 was largely excluded from Irs-1 complexes containing p59fyn, whereas Grb-2 and p85 occurred in the same Irs-1 complex. By comparison with the insulin receptor, p59fyn kinase phosphorylated a unique cohort of tyrosine residues in Irs-1. These results outline a role for p59fyn or other related Src-kinases during insulin and cytokine signaling.
Sun
X J
XJ
Research Division, Joslin Diabetes Center, Boston, Massachusetts 02215, USA.
Pons
S
S
Asano
T
T
Myers
M G
MG
Glasheen
E
E
White
M F
MF
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D006224:Cricetinae; D017931:DNA Primers; D004789:Enzyme Activation; D007328:Insulin / Q000494:pharmacology*; D055504:Insulin Receptor Substrate Proteins; D051379:Mice; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051076:Proto-Oncogene Proteins c-fyn; D015398:Signal Transduction; D013379:Substrate Specificity; D018909:src Homology Domains
D017931:DNA Primers; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; C526295:Irs1 protein, mouse; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; D011505:Protein-Tyrosine Kinases; C494960:Fyn protein, mouse; D051076:Proto-Oncogene Proteins c-fyn