Detection of a novel lymphocyte protein-tyrosine kinase by renaturation in polyacrylamide gels

Abstract

Protein kinase activity, including activity specific for the phosphorylation of tyrosine residues, can be detected among particulate fraction proteins of T cell lymphomas after separation by SDS-polyacrylamide gel electrophoresis. Putative protein kinases are detected by renaturation of enzyme activity directly within the gel following removal of detergent. LSTRA, a cell line that exhibits elevated levels of protein-tyrosine kinase activity, was found to express a predominant protein-tyrosine kinase of molecular weight 30,000. This same enzyme was present in T lymphocytes and other T lymphoid cell lines. Studies involving rapid preparation of protein fractions, limited proteolysis and one-dimensional peptide mapping did not demonstrate a direct relationship between the phosphorylated 30,000 dalton protein and the predominant 56,000 dalton phosphotyrosine containing protein that is observed following phosphorylation of LSTRA cell particulate fractions in vitro.