The cytosolic α-diacylglycerol kinase (DGK) was translocated to and tightly associated with the nuclear matrix when rat thymocytes and peripheral T-lymphocytes were stimulated with concanavalin A or anti-T-cell receptor antibody. This translocation occurred rather slowly and was completed in 3–4 h after cell stimulation. We also detected significant accumulation of nuclear phosphatidic acid interpreted as being formed by the translocated enzyme. The enzyme translocation is not directly linked to phosphoinositide turnover and protein phosphorylation, since phorbol myristate acetate and calcium ionophore did not affect the cellular DGKα and since we detected no covalent modification of the enzyme molecule. Although the mechanisms underlying the enzyme translocation remain unknown, our results indicate that DGKα participates in nuclear phospholipid metabolism occurring at the intermediate stage of lymphocyte activation.
