Characteristics of hepatic receptors for somatomedin c/insulin-like growth factor i and insulin in the developing human

Steven D. Chernausek, Dorothy C. Beach, Walter Banach, Mark A. Sperling

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36 Scopus citations

Abstract

Insulin and the somatomedins (Sms) are putative regulators of cell proliferation and metabolism in the fetus. Since the liver is a potential target tissue of these hormones during fetal life, we characterized the hepatic receptors for Sm-C/insulin like growth factor I (Sm-C/IGF-I) and insulin during the second trimester of human fetal development. Membrane-enriched fetal liver homogenates specifically bound 8.9 ± 1.5% (±sd) of added [125I]insulin and 5.1–7.2% of [125I]Sm-C/IGF-I. Binding of both hormones was constant from 12–20 weeks gestation and was much greater than that in adult liver membranes. Analysis of dose-response data indicated high affinity between each receptor and its respective ligand (Kd for the Sm-C/IGF-I receptor, 2.2 × 10−10 m; Kd for insulin receptor, 5.2 × 10−10 and 7.7 × 10−9 m). Limited cross-reactivity (∼1:1, 000) of insulin with the Sm-C/IGF-I receptor and Sm-C/IGF-I with the insulin receptor was found. Affinity labeling studies showed that each receptor possessed an approximately 135, 000-dalton subunit which was a part of a larger disulfide-linked complex. Thus, the human fetal liver has specific receptors for Sm-C/IGF-I and insulin that are similar to those described for other tissues in terms of both hormone-binding characteristics and subiinit structure, suggesting that these receptors mediate important cellular functions at this stage of fetal development.

Original languageEnglish
Pages (from-to)737-743
Number of pages7
JournalJournal of Clinical Endocrinology and Metabolism
Volume64
Issue number4
DOIs
StatePublished - Apr 1987
Externally publishedYes

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