Characterization of interleukin 2 stimulated 65-kilodalton phosphoprotein in human T cells.
We have characterized the cellular proteins which are rapidly phosphorylated by interleukin 2 (IL 2) in a human IL 2 dependent cell line. When treated with IL 2, the phosphorylation of five proteins, 65, 50, 37, 24, and 21 kDa, was found in IL 2 dependent cell lines by two-dimensional gel electrophoretic analysis. After cell conversion from an IL 2 dependent state to an IL 2 independent state, one of the five phosphoproteins, the 65-kDa protein, became constitutively phosphorylated even without addition of IL 2. Also, in other IL 2 independent cell lines, such as KUT-2 and HUT-102, constitutive phosphorylation of the 65-kDa protein occurred without IL 2-stimulation. So our researchers were focused on biochemical characterization of the 65-kDa protein. It was found that the 65-kDa protein was one of the major cellular proteins by comparing the results of two-dimensional gel electrophoretic analysis of [32P]Pi-labeled and [3H]leucine-labeled cellular proteins and peptide mapping analysis. Subcellular fractionation studies indicated that the 65-kDa protein is a cytosol protein. The 65-kDa protein was purified from cytosol of a human T cell line, and its amino acid composition and amino acid sequences of its three oligopeptides were determined. It was found that the 65-kDa protein is identical with 1-plastin.
Zu
Y
Y
Department of Pathology, Kyoto University, Japan.
Kohno
M
M
Kubota
I
I
Nishida
E
E
Hanaoka
M
M
Namba
Y
Y
D000595:Amino Acid Sequence; D002460:Cell Line; D003600:Cytosol / Q000032:analysis; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology*; D008562:Membrane Glycoproteins; D008840:Microfilament Proteins; D008969:Molecular Sequence Data; D010750:Phosphoproteins; D010766:Phosphorylation; D011506:Proteins / Q000302:isolation & purification*; D012694:Serine / Q000378:metabolism; D013347:Subcellular Fractions / Q000032:analysis; D013601:T-Lymphocytes / Q000378:metabolism*
D007376:Interleukin-2; D008562:Membrane Glycoproteins; D008840:Microfilament Proteins; D010750:Phosphoproteins; D011506:Proteins; C026742:plastin; D012694:Serine