A Novel Approach to Identify Two Distinct Receptor Binding Surfaces of Insulin-like Growth Factor II
Copyright policy )A Novel Approach to Identify Two Distinct Receptor Binding Surfaces of Insulin-like Growth Factor II
Very little is known about the residues important for the interaction of insulin-like growth factor II (IGF-II) with the type 1 IGF receptor (IGF-1R) and the insulin receptor (IR). Insulin, to which IGF-II is homologous, is proposed to cross-link opposite halves of the IR dimer through two receptor binding surfaces, site 1 and site 2. In the present study we have analyzed the contribution of IGF-II residues equivalent to insulin's two binding surfaces toward the interaction of IGF-II with the IGF-1R and IR. Four "site 1" and six "site 2" analogues were produced and analyzed in terms of IGF-1R and IR binding and activation. The results show that Val(43), Phe(28), and Val(14) (equivalent to site 1) are critical to IGF-1R and IR binding, whereas mutation to alanine of Gln(18) affects only IGF-1R and not IR binding. Alanine substitutions at Glu(12), Asp(15), Phe(19), Leu(53), and Glu(57) analogues resulted in significant (>2-fold) decreases in affinity for both the IGF-1R and IR. Furthermore, taking a novel approach using a monomeric, single-chain minimized IGF-1R we have defined a distinct second binding surface formed by Glu(12), Phe(19), Leu(53), and Glu(57) that potentially engages the IGF-1R at one or more of the FnIII domains.
- Case Western Reserve University United States
- University of Adelaide Australia
Protein Structure, BALB 3T3 Cells, Binding Sites, Mutation, Missense, Peptide Mapping, Receptor, Insulin, Protein Structure, Tertiary, Receptor, IGF Type 1, Mice, Amino Acid Substitution, Insulin-Like Growth Factor II, Mutation, 616, Insulin, Animals, Humans, IGF Type 1, Missense, Dimerization, Tertiary, Receptor, Protein Binding
Protein Structure, BALB 3T3 Cells, Binding Sites, Mutation, Missense, Peptide Mapping, Receptor, Insulin, Protein Structure, Tertiary, Receptor, IGF Type 1, Mice, Amino Acid Substitution, Insulin-Like Growth Factor II, Mutation, 616, Insulin, Animals, Humans, IGF Type 1, Missense, Dimerization, Tertiary, Receptor, Protein Binding
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