Abstract
Like insulin-like growth factor binding protein-3 (IGFBP-3), IGFBP-5 forms a ternary complex with insulin-like growth factor (IGF)-I or IGF-II, and the acid-labile subunit (ALS). The study of IGFBP-5/IGFBP-6 chimeric proteins with amino-terminal and middle domain swaps, has revealed the existence of a site in the middle domain of IGFBP-5, that binds to ALS in the absence of the IGFBP-5 carboxy-terminal domain. An IGFBP-6 chimeric protein containing the central domain of IGFBP-5 complexed efficiently with ALS, and a carboxy-terminally truncated IGFBP-5 mutant, IGFBP-5'(1-169), also bound to ALS in the presence of IGFs, although with much less potency than full length rhIGFBP-5. In contrast to the latter, IGFBP-5(1-169) preferentially formed ternary complexes with IGF-II rather than IGF-I. These results indicate that a site which binds ALS exists in IGFBP-5 mutants which lack the IGFBP-5 carboxy-terminal domain.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Binding Sites
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Binding, Competitive
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Carrier Proteins / chemistry*
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Carrier Proteins / genetics
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Cross-Linking Reagents
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Electrophoresis, Polyacrylamide Gel
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Glycoproteins / chemistry*
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Glycoproteins / genetics
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Humans
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Insulin-Like Growth Factor Binding Protein 5 / chemistry*
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Insulin-Like Growth Factor Binding Protein 5 / genetics
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Insulin-Like Growth Factor Binding Protein 6 / chemistry
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Insulin-Like Growth Factor Binding Protein 6 / genetics
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Insulin-Like Growth Factor I / chemistry
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Insulin-Like Growth Factor II / chemistry
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Precipitin Tests
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Recombinant Proteins / chemistry
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Silver Staining
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Somatomedins / chemistry*
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Somatomedins / genetics
Substances
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Carrier Proteins
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Cross-Linking Reagents
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Glycoproteins
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Insulin-Like Growth Factor Binding Protein 5
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Insulin-Like Growth Factor Binding Protein 6
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Recombinant Proteins
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Somatomedins
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insulin-like growth factor binding protein, acid labile subunit
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Insulin-Like Growth Factor I
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Insulin-Like Growth Factor II