pervanadate and Leukemia--T-Cell

A glutathione-S-transferase-src-homology domain 2 (GST-SH2) fusion protein was employed to identify molecules interacting with the protein tyrosine kinase p59fyn. Among several proteins which bound to the fyn SH2 domain in lysates of human Jurkat T lymphocytes, alpha- and beta-tubulin were identified by N-terminal sequencing. Further analysis established that alpha-tubulin exists as a tyrosine-phosphorylated protein in Jurkat cells, where it interacts with p59fyn, but not with p56lck. By contrast, in untransformed resting human T lymphocytes alpha-tubulin is not detectable as a tyrosine phosphorylated protein. However, following T cell activation, it becomes rapidly phosphorylated on tyrosine residues and subsequently associates with the SH2 domain of fyn. Interestingly, constitutively tyrosine-phosphorylated alpha-tubulin that is able to interact with the fyn-SH2 domain is expressed in peripheral blood T lymphoblasts isolated from leukemic patients in the absence of external stimulation.

Topics: Amino Acid Sequence; Humans; Leukemia, T-Cell; Lymphocyte Activation; Lymphoma, T-Cell; Molecular Sequence Data; Phosphoric Monoester Hydrolases; Phosphorylation; Precipitin Tests; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-fyn; src Homology Domains; T-Lymphocytes; Tubulin; Tumor Cells, Cultured; Tyrosine; Vanadates