Mutation of Three Critical Amino Acids of the N-Terminal Domain of IGF-Binding Protein-3 Essential for High Affinity IGF Binding
| Autor: | Ron G. Rosenfeld, M. Ahlsén, Elizabeth M. Wilson, Caroline K. Buckway, Youngman Oh, Peter Bang |
|---|---|
| Rok vydání: | 2001 |
| Předmět: |
medicine.medical_specialty
Recombinant Fusion Proteins Endocrinology Diabetes and Metabolism Molecular Sequence Data Clinical Biochemistry Mutant Biology Biochemistry Receptor IGF Type 1 Endocrinology Somatomedins Internal medicine medicine Animals Amino Acid Sequence Phosphorylation Binding site Peptide sequence chemistry.chemical_classification Binding Sites Biochemistry (medical) Protein superfamily Protein tertiary structure Amino acid Insulin-Like Growth Factor Binding Protein 3 chemistry COS Cells Mutation Glycine Baculoviridae |
| Zdroj: | The Journal of Clinical Endocrinology & Metabolism. 86:4943-4950 |
| ISSN: | 1945-7197 0021-972X |
| DOI: | 10.1210/jcem.86.10.7936 |
| Popis: | The N-terminal domain is conserved in all members of the IGF-binding protein superfamily. Most recently, studies have demonstrated the importance of an IGF-binding protein N-terminal hydrophobic pocket for IGF binding. To examine more critically the amino acids important for IGF binding within the full-length IGF-binding protein-3 protein while minimizing changes in the tertiary structure, we targeted residues I56, L80, and L81 within the proposed hydrophobic pocket for mutation. With a single change at these sites to the nonconserved glycine there was a notable decrease in binding. A greater reduction was seen when both L80 and L81 were substituted with glycine, and complete loss of affinity for IGF-I and IGF-II occurred when all three targeted amino acids were changed to glycine. Furthermore, the ability of the IGF-binding protein-3 mutants to inhibit IGF-I-stimulated phosphorylation of its receptor was a reflection of their affinity for IGF, with the lowest affinity mutants having the least inhibitory effect.These studies, thus, support the hypothesis that an N-terminal hydrophobic pocket is the primary site of high affinity binding of IGF to IGF-binding protein-3. The mutants provide a tool for future studies directed at IGF-dependent and IGF-independent actions of IGF-binding protein-3. |
| Databáze: | OpenAIRE |
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