The adapter protein Grb10 associates preferentially with the insulin receptor as compared with the IGF-I receptor in mouse fibroblasts.
To identify receptor-associated proteins that may contribute to the specificity of insulin and IGF-I signaling responses, a mouse embryo library was screened using the yeast two-hybrid system. Multiple receptor-interactive clones encoding the SH2 domain of the adapter protein Grb10 were isolated. Subsequent cloning of the full-length Grb10 sequence from a mouse fat cDNA library defined a previously unknown Grb10 variant, that appears to be the predominant isoform in mouse tissues. Receptor-deficient R- cells (fibroblasts from mice with homologous disruption of the IGF-I receptor gene) and transfected R- cells expressing either insulin receptors (R-IR cells) or IGF-I receptors (R+ cells) were used to investigate the specificity of Grb10 interaction with the two related receptors. Hormone-activated insulin receptors in R-IR cells coprecipitated with three species, all recognized as Grb10 isoforms by specific Grb10 antibody. Under the same conditions, Grb10 was essentially undetectable in IGF-I receptor immunoprecipitates from stimulated R+ cells. Grb10 association with insulin receptors was maximal at 10 nM insulin stimulation and sustained from 5-10 min after hormone stimulation in R-IR cells. In conclusion, Grb10 interacts preferentially with insulin vs. IGF-I receptors in intact cells and, thus, may have a role in mediating insulin receptor-specific cellular responses.
Laviola
L
L
Research Division, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts 02215, USA.
Giorgino
F
F
Chow
J C
JC
Baquero
J A
JA
Hansen
H
H
Ooi
J
J
Zhu
J
J
Riedel
H
H
Smith
R J
RJ
D000818:Animals; D015152:Blotting, Northern; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000032:analysis; D004587:Electrophoresis, Agar Gel; D004591:Electrophoresis, Polyacrylamide Gel; D005347:Fibroblasts; D051383:GRB10 Adaptor Protein; D005786:Gene Expression Regulation; D015723:Gene Library; D014644:Genetic Variation; D015151:Immunoblotting; D007328:Insulin / Q000494:pharmacology; D007536:Isomerism; D007763:Lac Operon; D051379:Mice; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D016133:Polymerase Chain Reaction; D011233:Precipitin Tests; D011506:Proteins / Q000235:genetics* / Q000276:immunology / Q000502:physiology*; D017526:Receptor, IGF Type 1 / Q000235:genetics* / Q000502:physiology*; D011972:Receptor, Insulin / Q000235:genetics* / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D014162:Transfection; D015003:Yeasts / Q000235:genetics
D017931:DNA Primers; D018076:DNA, Complementary; C495959:Grb10 protein, mouse; D007328:Insulin; D011506:Proteins; D051383:GRB10 Adaptor Protein; D017526:Receptor, IGF Type 1; D011972:Receptor, Insulin