Receptors for insulin-like growth factors I and II in rat gastrointestinal epithelium

Journal Article · Tue Mar 01 04:00:00 EST 1988 · American Journal of Physiology; (USA)

OSTI ID:6810482

Laburthe, M; Rouyer-Ressard, C; Gammeltoft, S ^[1]

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1. Institut National de La Sante et de la Recherche Medicale, Villejuif (France) Bispebjerg Hospital, Copenhagen (Denmark)

Distinct receptors for insulin-like growth factors (IGFs) have been characterized in rat intestinal epithelium using {sup 125}I-labeled IGF-I and {sup 125}I-labeled IGF-II. In jejunal epithelial plasma membranes, IGF-I receptors were observed with a dissociation constant (K{sub d}) of 7.2 nM and a binding capacity of 0.56 pmol/mg protein. Distinct IGF-II receptors were also found with a K{sub d} of 9.5 nM and a binding capacity of 2.61 pmol/mg protein. For IGF-I receptors the following order of affinity was observed: IGF-I > IGF-II > insulin > proinsulin. IGF-II receptors recognize IGF-II with a 20-fold higher affinity than IGF-I and display no cross-reactivity with insulin and proinsulin. Affinity labeling of intestinal membranes also discriminates between the two types of receptors, revealing a radioligand-receptor complex of relative molecular weight (M{sub r}) 130,000 using {sup 125}I-IGF-I and 250,000 for {sup 125}I-IGF-II under reducing conditions. Separation of proliferative crypt cells from mature villus cells in the small intestine makes it possible to show that a gradient of IGF receptors is present along the crypt-villus axis. {sup 125}I-IGF-I and {sup 125}I-IGF-II binding is 4.0- and 1.8-fold higher in crypt cells than in villus cells, respectively. Specific {sup 125}I-IGF binding is detectable throughout the gastrointestinal tract. The level of IGF binding is similar in stomach, small intestine, and cecum, but higher values are observed in colon.

• OSTI ID: 6810482
• Journal Information: American Journal of Physiology; (USA), Journal Name: American Journal of Physiology; (USA) Vol. 254:3; ISSN 0002-9513; ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMAL TISSUES
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BODY
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
ELECTRON CAPTURE RADIOISOTOPES
EPITHELIUM
GASTROINTESTINAL TRACT
GROWTH FACTORS
HORMONES
INSULIN
INTERMEDIATE MASS NUCLEI
INTESTINES
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LARGE INTESTINE
LIGANDS
MEMBRANE PROTEINS
MITOGENS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PEPTIDE HORMONES
PROTEINS
RADIOISOTOPES
RADIORECEPTOR ASSAY
REACTION KINETICS
RECEPTORS
SMALL INTESTINE
STOMACH
TISSUES
TRACER TECHNIQUES