Down-modulation of receptors for phorbol ester tumor promoter in primary epidermal cells
The specific (20-/sup 3/H)phorbol 12,13-dibutyrate ((/sup 3/H)PDBu) binding to intact epidermal cells displayed the phenomenon of down-modulation, i.e., the specific binding of (/sup 3/H)PDBu to its receptors on primary epidermal cells reached a maximum within 1 h and steadily declined thereafter. The apparent down-modulation of radiolabel resulted from a partial loss in the total number of receptors; the affinity of receptors for the ligand was essentially unchanged. A number of agents such as chloroquine, methylamine, or arginine which are known to prevent clustering, down-modulation, and/or internalization of several hormone receptors did not affect the down-modulation of phorbol ester receptors. Furthermore, cycloheximide had no effect either on down-modulation or on the binding capacity of cells. The surface binding capacity of down-modulated cells following a 90-min incubation with unlabeled ligand was almost returned to normal within 1 h. The effect of the antidepressant drug chlorpromazine, which is known to interact with calmodulin, on (/sup 3/H)PDBu binding was also investigated. Our data indicate that the effect of chlorpromazine on (/sup 3/H)PDBu binding is probably unrelated to its calmodulin-binding activity.
- Research Organization:
- Oak Ridge National Lab., TN
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 5148739
- Journal Information:
- Carcinogenesis (N.Y.); (United States), Vol. 3:9
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PHORBOL ESTERS
RECEPTORS
TUMOR PROMOTERS
BIOCHEMISTRY
ANIMAL CELLS
CARCINOGENESIS
EPIDERMIS
MICE
TRITIUM COMPOUNDS
ANIMAL TISSUES
ANIMALS
BODY
CARCINOGENS
CHEMISTRY
EPITHELIUM
ESTERS
LABELLED COMPOUNDS
MAMMALS
ORGANIC COMPOUNDS
ORGANS
PATHOGENESIS
PROMOTERS
RODENTS
SKIN
TISSUES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques
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