An antipeptide antibody that specifically inhibits insulin receptor autophosphorylation and protein kinase activity.
Two site-specific antibodies that immunoprecipitate the human insulin receptor have been prepared by immunizing rabbits with chemically synthesized peptides derived from the cDNA-predicted amino acid sequence of the beta subunit of the proreceptor. Antibodies to the carboxyl terminus (AbP5) and to a domain around tyrosine-960 (AbP4) specifically recognize the beta subunit of the receptor on immunoblots. Both antibodies immunoprecipitated 125I-labeled insulin-receptor complexes and the autophosphorylated receptor. Although neither antibody inhibited insulin binding to the receptor, both insulin-dependent autophosphorylation and exogenous substrate phosphorylation were inhibited by AbP4. Inhibition by AbP4 was dependent upon the phosphorylation state of the receptor; it was not detected when the receptor was autophosphorylated prior to addition of AbP4. AbP4 did not inhibit activity of the related epidermal growth factor (EGF)-receptor tyrosine protein kinase nor did it inhibit the activity of cAMP-dependent kinase or protein kinase C. The observation that an antibody directed to residues 952-967 of the proreceptor neutralizes the protein kinase activity of the beta subunit suggests that this region may play a critical role in the function of the hormone-dependent, protein tyrosine-specific kinase activity of the insulin receptor.
Herrera
R
R
Petruzzelli
L
L
Thomas
N
N
Bramson
H N
HN
Kaiser
E T
ET
Rosen
O M
OM
D000595:Amino Acid Sequence; D000906:Antibodies / Q000276:immunology*; D000918:Antibody Specificity; D000937:Antigen-Antibody Reactions; D000939:Epitopes; D006801:Humans; D009842:Oligopeptides / Q000138:chemical synthesis / Q000276:immunology; D010750:Phosphoproteins / Q000276:immunology; D010766:Phosphorylation; D011498:Protein Precursors / Q000276:immunology / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000276:immunology* / Q000378:metabolism; D011972:Receptor, Insulin / Q000276:immunology* / Q000378:metabolism
D000906:Antibodies; D000939:Epitopes; D009842:Oligopeptides; D010750:Phosphoproteins; D011498:Protein Precursors; D011505:Protein-Tyrosine Kinases; D011972:Receptor, Insulin