Activation of protein kinase C modulates the expression of the T3/T cell antigen receptor complex on human T lymphocytes

Activators of protein kinase C induced a rapid decrease (within 15 min) in the surface expression of the T3 antigen and T-lymphocyte antigen receptor (Ti) on HPB-ALL cells, and a concomitant phosphorylation of the T3 γ and δ polypeptides; the γ chain was more extensively phosphorylated than the δ chain. No phosphorylation of the T3 ∈ chain and the Ti α and β polypeptides was detected. Evidence was obtained that the T3 γ chain is phosphorylated only on serine residues.