Identification of a type 6 protein ser/thr phosphatase regulated by interleukin-2 stimulation.
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.
Filali
M
M
Department of Pathology and Laboratory Medicine, University of Pennsylvania, School of Medicine, Philadelphia 19104-4283, USA.
Li
S
S
Kim
H W
HW
Wadzinski
B
B
Kamoun
M
M
D000595:Amino Acid Sequence; D002453:Cell Cycle; D003001:Cloning, Molecular; D018076:DNA, Complementary; D015180:Electrophoresis, Gel, Two-Dimensional; D004789:Enzyme Activation; D020224:Expressed Sequence Tags; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology*; D019169:Jurkat Cells; D008214:Lymphocytes / Q000166:cytology / Q000201:enzymology; D008969:Molecular Sequence Data; D010749:Phosphoprotein Phosphatases / Q000302:isolation & purification / Q000378:metabolism*; D010766:Phosphorylation; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D007376:Interleukin-2; D010749:Phosphoprotein Phosphatases