Identification of a type 6 protein ser/thr phosphatase regulated by interleukin-2 stimulation.

Filali M, Li S, Kim HW, Wadzinski B, Kamoun M
J Cell Biochem. 1999 73 (2): 153-63

PMID: 10227379

We have identified a 36 kD phosphoprotein that forms a complex with spliceosomal small nuclear ribonucleoproteins in lymphocyte extracts. This 36 kD protein is differentially phosphorylated in transformed human lymphoid cell lines and is regulated by IL-2 in peripheral blood T cells. We purified the 36 kD protein from human lymphocytes by employing a combination of immuno-affinity chromatography and preparative two-dimensional gel electrophoresis. Internal amino acid sequence analysis of the purified protein yielded two peptides that had perfect matches with sequences in the human protein serine/threonine phosphatase 6 (PP6). Using degenerate primers corresponding to the peptides, we obtained from a human T lymphocyte cDNA library a DNA fragment whose sequence is homologous to an EST cDNA clone (R05547). The predicted amino acid sequence of this clone showed over 98% sequence identity to human PP6. The identification of an IL-2 regulated type 6 protein serine/threonine phosphatase in lymphocytes was further substantiated by immunoblotting with anti-peptide antibodies. These findings suggest that PP6 is a component of a signaling pathway regulating cell cycle progression in response to IL-2 receptor stimulation.

MeSH Terms (15)

Amino Acid Sequence Cell Cycle Cloning, Molecular DNA, Complementary Electrophoresis, Gel, Two-Dimensional Enzyme Activation Expressed Sequence Tags Humans Interleukin-2 Jurkat Cells Lymphocytes Molecular Sequence Data Phosphoprotein Phosphatases Phosphorylation Sequence Homology, Amino Acid

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