Insulin-like growth factor-II receptors in cultured rat hepatocytes: regulation by cell density

Journal Article · Tue Dec 01 00:00:00 EST 1987 · J. Cell. Physiol.; (United States)

DOI:https://doi.org/10.1002/jcp.1041330314· OSTI ID:5562600

Scott, C D; Baxter, R C

Insulin-like growth factor-II (IGF-II) receptors in primary cultures of adult rat hepatocytes were characterized and their regulation by cell density examined. In hepatocytes cultured at 5 X 10(5) cells per 3.8 cm2 plate (/sup 125/I)IGF-II bound to specific, high affinity receptors (Ka = 4.4 +/- 0.5 X 10(9) l/mol). Less than 1% cross-reactivity by IGF-I and no cross-reactivity by insulin were observed. IGF-II binding increased when cells were permeabilized with 0.01% digitonin, suggesting the presence of an intracellular receptor pool. Determined by Scatchard analysis and by polyacrylamide gel electrophoresis after affinity labeling, the higher binding was due solely to an increase in binding sites present on 220 kDa type II IGF receptors. In hepatocytes cultured at low densities, the number of cell surface receptors increased markedly, from 10-20,000 receptors per cell at a culture density of 6 X 10(5) cells/well to 70-80,000 receptors per cell at 0.38 X 10(5) cells/well. The increase was not due simply to the exposure of receptors from the intracellular pool, as a density-related increase in receptors was also seen in cells permeabilized with digitonin. There was no evidence that IGF binding proteins, either secreted by hepatocytes or present in fetal calf serum, had any effect on the measurement of receptor concentration or affinity. We conclude that rat hepatocytes in primary culture contain specific IGF-II receptors and that both cell surface and intracellular receptors are regulated by cell density.

• Research Organization: Royal Prince Alfred Hospital, Camperdown, Australia
• OSTI ID: 5562600
• Journal Information: J. Cell. Physiol.; (United States), Vol. 133:3
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
GROWTH FACTORS
BIOCHEMICAL REACTION KINETICS
RECEPTORS
CHEMICAL COMPOSITION
CELL CULTURES
DENSITY
ELECTROPHORESIS
INSULIN
IODINE 125
LIVER CELLS
RATS
TRACER TECHNIQUES
ANIMAL CELLS
ANIMALS
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ELECTRON CAPTURE RADIOISOTOPES
HORMONES
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
MAMMALS
MEMBRANE PROTEINS
MITOGENS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PEPTIDE HORMONES
PHYSICAL PROPERTIES
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RODENTS
SOMATIC CELLS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques