Phosphorylation of the lymphoid cell kinase p56lck is stimulated by micromolar concentrations of Zn2+

Abstract

In particulate fraction from LSTRA lymphoma cells, tyrosine phosphorylation of the lymphoid specific tyrosine kinase p56^lck is elicited by Zn²⁺ in the absence of other divalent cations. Zn²⁺ alone also induces autophosphorylation of immunoprecipitated p56^lck. The effect of Zn²⁺ is dose dependent; it is detected at concentrations of Zn²⁺ as low as 5 μM and reaches a maximum at 100 μM Zn²⁺. Among other divalent cations tested. Mn²⁺, and Co²⁺ to a lesser extent, were also effective. Zn²⁺ also stimulated p56^lck phosphorylation in the presence of Mg²⁺ ions at physiological concentration, whereas orthovanadate had no effect. These results suggest that Zn²⁺ activates the autophosphorylation of p56^lck; this fact could be related with the stimulating effect of Zn²⁺ in the activation of T lymphocytes.