Specific binding of phorbol esters to Friend erythroleukemia cells--general properties, down regulation and relationship to cell differentiation
Specific and saturable binding sites for (20-/sup 3/H)phorbol 12,13-dibutyrate ((/sup 3/H)PDBu) were demonstrated in tact Friend erythroleukemia cells (FELC), in which inducible erythroid differentiation is reversibly inhibited by phorbol esters. The binding of (/sup 3/H)PDBu to intact cells was maximal within only 15 min of incubation at 37 degrees C, after which there was a gradual decrease; binding at 4 degrees C however, was alow process, requiring greater than 180 min for maximal binding. A Scatchard analysis showed that the dissociation constant for binding of (/sup 3/H)PDBu is 8.3 nM; at saturation, approximately 1.75 x 10(5) molecules of (/sup 3/H)PDBu are bound per cell. When FELC were induced to differentiate with 4mM hexameethylene bisacetamide (approximately 80% of cells were benzidine-positive), a slight decrease (10-20%) in the number of binding sites at saturation was seen, but the dissociation constant was not changed. When the cells were precultured with non-radioactive phorbol esters, a significant decrease in (/sup 3/H)PDBu binding was observed, suggesting a homologous down regulation of phorbol ester receptors. Scatchard analysis indicated that the decrease in (/sup 3/H)PDBu binding was due to a decrease in the number of binding sites and not to a change in affinity. Such specific phorbol ester binding sites might mediate a number of biochemical and biological effects of phorbol esters on FELC.
- Research Organization:
- International Agency for Research on Cancer, Lyon Cedex, France
- OSTI ID:
- 6564576
- Journal Information:
- Carcinogenesis (N.Y.); (United States), Journal Name: Carcinogenesis (N.Y.); (United States) Vol. 3:8; ISSN CRNGD
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
550301 -- Cytology-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BIOCHEMICAL REACTION KINETICS
BIOCHEMISTRY
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
CARCINOGENS
CELL CULTURES
CHEMISTRY
DISEASES
ERYTHROCYTES
ESTERS
HEMIC DISEASES
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LEUKEMIA
MATERIALS
NEOPLASMS
ORGANIC COMPOUNDS
PHORBOL ESTERS
REACTION KINETICS
RECEPTORS
TEMPERATURE DEPENDENCE
TRACER TECHNIQUES
TRITIUM COMPOUNDS