N-terminal deletion mutants of insulin-like growth factor-II (IGF-II) show Thr super(7) and Leu super(8) important for binding to insulin and IGF-I receptors and Leu super(8) critical for all IGF-II functions

To define the role of the N-terminal region of insulin-like growth factor-II (IGF-II) in its binding to insulin and IGF receptors, deletion mutants des-(1-5)-, des-(1-7)-, and des-(1-8)-recombinant (r) IGF-II, and the Gly super(8) for Leu substitution mutant of rIGF-II were prepared by site-directed...

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Published in:The Journal of biological chemistry 1995-01, Vol.270 (30), p.18013-18018
Main Authors: Hashimoto, R, Fujiwara, H, Higashihashi, N, Enjoh-Kimura, T, Terasawa, H, Fujita-Yamaguchi, Y, Inagaki, F, Perdue, J F, Sakano, K-I
Format: Article
Language:English
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Escherichia coli
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Summary:To define the role of the N-terminal region of insulin-like growth factor-II (IGF-II) in its binding to insulin and IGF receptors, deletion mutants des-(1-5)-, des-(1-7)-, and des-(1-8)-recombinant (r) IGF-II, and the Gly super(8) for Leu substitution mutant of rIGF-II were prepared by site-directed mutagenesis, expressed in Escherichia coli, and purified. The binding affinity and mitogenic activity of these rIGF-II mutants as well as commercially available des-(1-6)-rIGF-II were analyzed. While the relative affinity of des-(1-5)- and des-(1-6)-rIGF-II for purified human insulin and IGF-I receptors remained at greater than or equal to 50% levels of that of rIGF-II, the affinity of des-(1-7)-rIGF-II decreased to similar to 10% and similar to 3%, respectively, of that of rIGF-II. When the octapeptide including Leu super(8) was removed prior to the Cys super(9)-Cys super(47) intrachain bond, the relative affinity of this deletion mutant, des-(1-8)-rIGF-II, for these receptors dramatically decreased to
ISSN:0021-9258