CD148, a membrane protein tyrosine phosphatase, is able to induce tyrosine phosphorylation on human lymphocytes

CD148 is a new cluster of differentiation defined in the VI International Workshop on Leucocyte Differentiation Antigens. It has been identified as the hematopoietic form of a formerly described membrane protein tyrosine phosphatase called HPTP eta/ DEP-1. Previous data have demonstrated that this molecule is able to give rise to [Ca2+]i increase. In the present work we show its capability to induce protein tyrosine phosphorylation in human lymphocytes in spite of its intrinsic protein tyrosine phosphatase activity. The induction of kinase activity suggests the involvement of some protein tyrosine kinase based signaling pathway. The activation of this postulated kinase could be carried out through a direct association or via an adapter molecule.