title: Two major tyrosine protein kinases of resting human T lymphocytes are down-regulated following mitotic stimulation.
abstract: Human lymphocyte tyrosine protein kinases (TPKs) have been analyzed by gel-filtration chromatography. The major TPK species with activity towards an exogenous tyrosine-containing peptide had molecular masses of 70-100 kDa (TPK I) and 35-40 kDa (TPK II). TPKs I and II were distinct from the well-characterized autophosphorylating lymphoid cell TPK, pp56lck [(1983) J. Biol. Chem. 258, 10738-10742]. Both TPK I and TPK II were down-regulated following mitogenic stimulation of lymphocytes with phytohaemagglutinin. By contrast, pp56lck remained clearly detectable in stimulated lymphocytes. We suggest that TPKs I and II may play a role in the regulation of the lymphocyte cell cycle.
mesh_terms: D002453:Cell Cycle; D006801:Humans; D008213:Lymphocyte Activation; D008970:Molecular Weight; D010750:Phosphoproteins / Q000378:metabolism; D010835:Phytohemagglutinins / Q000494:pharmacology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D013601:T-Lymphocytes / Q000166:cytology / Q000201:enzymology*
chemical_list: D010750:Phosphoproteins; D010835:Phytohemagglutinins; D011505:Protein-Tyrosine Kinases