Insulin-like growth factor I (IGF I) receptor autophosphorylation and kinase activity. Effect of a human polyclonal antibody (pIgG)
IGF I receptor is a tyrosine kinase capable of phosphorylating the receptor itself and other substrates. A high degree of homology does exist in tyrosine kinase domain among receptors for several polypeptide growth factor receptors and this enzymic activity has been indicated as a possible mediator of biological action. Nevertheless growth factor receptors possess peculiar specificities both in their functions and tissue distribution. A human polyclonal IgG (pIgG), previously characterized as anti insulin receptor antibody, able to inhibit insulin receptor kinase activity, was used to further investigate subunit homologies and differences in antigenicity and functional regulation between IGF I and insulin receptors, IGF I receptor tyrosine kinase was stimulated by a IGF I analog (aIGF I), produced by DNA recombinant technology, pIgG was able to inhibit IGF I receptor kinase activity, thus revealing antigenic homologies between the kinase domains of insulin and IGF I receptors. However the more pronounced inhibition of IGF I receptor-compared with insulin receptor kinase activity by pIgG suggests the existence of different regulatory mechanisms.
D000937:Antigen-Antibody Reactions; D066298:In Vitro Techniques; D007334:Insulin-Like Growth Factor I / Q000031:analogs & derivatives / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D010920:Placenta / Q000032:analysis; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000276:immunology / Q000378:metabolism*; D017451:Receptors, Somatomedin; D011994:Recombinant Proteins / Q000378:metabolism
D010750:Phosphoproteins; D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I; D011505:Protein-Tyrosine Kinases