Structural domains of the insulin receptor and IGF receptor required for dimerisation and ligand binding

• Published in: FEBS letters 2000-02, Vol.467 (2-3), p.226-230
• Main Authors: Molina, L, Marino-Buslje, C, Quinn, D.R, Siddle, K
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Binding Sites; Binding, Competitive; C-terminal, carboxyl terminal; CHO Cells; CHO, Chinese hamster ovary; Cricetinae; CYS, cysteine-rich domain; Dimerization; DNA, Complementary - biosynthesis; DTT, dithiothreitol; F, fibronectin type III; IGF, insulin-like growth factor; IGFR, type I insulin-like growth factor receptor; Insulin; Insulin-like growth factor; IR, insulin receptor; Ligand binding; Ligands; Molecular Sequence Data; N-terminal, amino terminal; Peptide Fragments - biosynthesis; Peptide Fragments - genetics; Receptor; Receptor, Insulin - chemistry; Receptor, Insulin - genetics; Receptors, Somatomedin - chemistry; Receptors, Somatomedin - genetics; Structural domain
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/S0014-5793(00)01161-3

We investigated structural requirements for dimerisation and ligand binding of insulin/IGF receptors. Soluble receptor fragments consisting of N-terminal domains (L1/CYS/L2, L1/CYS/L2/F0) or fibronectin domains (F0/F1/F2, F1/F2) were expressed in CHO cells. Fragments containing F0 or F1 domains were secreted as disulphide-linked dimers, and those consisting of L1/CYS/L2 domains as monomers. None of these proteins bound ligand. However, when a peptide of 16 amino acids from the α-subunit C-terminus was fused to the C-terminus of L1/CYS/L2, the monomeric insulin and IGF receptor constructs bound their respective ligands with affinity only 10-fold lower than native receptors.