Activators of protein kinase C down-regulate and phosphorylate the T3/T-cell antigen receptor complex of human T lymphocytes

D. A. Cantrell, A. A. Davies, M. J. Crumpton

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As judged by indirect immunofluorescence, phorbol 12,13-dibutyrate and 1-oleoyl-2-acetylglycerol induced a rapid, concentration-dependent decrease of about 50% in the surface expression of the T3 antigen on human T lymphoblasts, and of T3 and the T-cell antigen receptor on HPB-ALL cells. Direct binding experiments using 125I-labeled antibody indicated that the reductin in T3 expression corresponded to a decrease in the number of antigen molecules rather than a change in their affinity. Biochemical analyses revealed that phorbol dibutyrate induced a rapid, prominent phosphorylation of the T3 M(r) 26,000 γ chain and to a lesser extent of the M(r) 21,000 δ chain. No phosphorylation of the T3 ε chain or of the α and β subunits of the T-cell antigen receptor was detected. The data suggest that protein kinase C induces a phosphorylation of the T3 γ and δ chains that may lead to the down-regulation of the T3/T-cell antigen receptor complex.

Original languageEnglish
Pages (from-to)8158-8162
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number23
Publication statusPublished - 1 Dec 1985


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