title: Tertiary structures, receptor binding, and antigenicity of insulinlike growth factors.
abstract: Three-dimensional models for human insulinlike growth factors (IGF-I and IGF-II) have been constructed by using interactive molecular graphics. It is suggested that the two growth factors have structures in which the A and B chains and the hydrophobic cores are identical to those of insulin. The conformations of the connecting peptides and COOH-terminal extensions are predicted by statistical methods but the structures are limited by the constraints implied by the insulinlike part. The models explain the nonsuppressibility by anti-insulin antibodies of the IGFs and show that part of the insulin receptor-binding region is conserved, which explains the growth factors' ability to bind insulin receptors.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000936:Antigen-Antibody Complex; D000939:Epitopes / Q000032:analysis*; D007106:Immune Sera; D007328:Insulin / Q000378:metabolism*; D046911:Macromolecular Substances; D008958:Models, Molecular; D010455:Peptides / Q000378:metabolism*; D011487:Protein Conformation; D011956:Receptors, Cell Surface / Q000276:immunology / Q000378:metabolism*; D017451:Receptors, Somatomedin; D013002:Somatomedins / Q000378:metabolism*
chemical_list: D000936:Antigen-Antibody Complex; D000939:Epitopes; D007106:Immune Sera; D007328:Insulin; D046911:Macromolecular Substances; D010455:Peptides; D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D013002:Somatomedins