title: Determinants for the interaction between Janus kinase 2 and protein phosphatase 2A.
abstract: We have shown that the serine/threonine protein phosphatase 2A (PP2A) associates with the Jak2 tyrosine kinase in a myeloid progenitor line. In this study, we characterized the regions of Jak2 and PP2A responsible for association and evaluated the functional consequences of association. We demonstrate that PP2A interacts with truncated forms of Jak2 containing the JH1 catalytic domain. Using GST fusion proteins, we show that the isolated JH1 and JH3 domains of Jak2 bind directly to PP2A. Jak2 contains putative PP2A binding sequences (LXXLL) in the JH1 domain (residues 1078-1082) and in the JH3 domain (residues 474-478). Mutation of the LXXLL sequence in the JH1 domain decreased PP2A binding in vitro, while mutation of the similar JH3 sequence did not affect PP2A binding. We analyzed full-length Jak2 bearing the LXXLL mutation in Cos-7 cells for association with PP2A. The JH1 mutation impaired Jak2 activity and had a modest effect on PP2A binding. Finally, we show that a mutant form of the PP2A catalytic subunit lacking a site for phosphorylation (Y307F) binds more tightly to Jak2 than wild-type PP2A, consistent with a model where phosphorylation disrupts the Jak2-PP2A interaction.
authors.affiliation: Department of Physiology and Biophysics, School of Medicine, State University of New York at Stony Brook, Stony Brook, NY 11794-8661, USA.
authors.forename: Noriko
authors.initials: N
authors.lastname: Yokoyama
authors.forename: Nancy C
authors.initials: NC
authors.lastname: Reich
authors.forename: W Todd
authors.initials: WT
authors.lastname: Miller
mesh_terms: D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D020134:Catalytic Domain; D002460:Cell Line; D002522:Chlorocebus aethiops; D004926:Escherichia coli / Q000235:genetics; D005982:Glutathione Transferase / Q000378:metabolism; D053614:Janus Kinase 2; D051379:Mice; D016297:Mutagenesis, Site-Directed; D010749:Phosphoprotein Phosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D017354:Point Mutation; D011485:Protein Binding; D054648:Protein Phosphatase 2; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D005982:Glutathione Transferase; D011505:Protein-Tyrosine Kinases; C507926:Jak2 protein, mouse; D053614:Janus Kinase 2; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2