title: Description of an IL-1-responsive kinase that phosphorylates the K protein. Enhancement of phosphorylation by selective DNA and RNA motifs.
abstract: The K protein was first identified in the heterogeneous ribonucleoprotein particle (hnRNP). Subsequently, K protein was shown to bind sequence-specific single-and double-stranded DNA, stimulate transcription, and bind Src, Fyn, Lyn, and Vav via SH3 interactions. The K protein also binds to the kappa B enhancer motif which stimulates its phosphorylation in vitro by an associated serine/threonine kinase. To gain more insight into this unique nucleic acid-dependent phosphorylation process, we set out to examine the regulation of this kinase. We demonstrate that the K protein exists in a complex with an IL-1-responsive kinase and that phosphorylation of the K protein by this kinase is augmented by either cognate DNA or RNA sequences. The IL-1-responsive kinase activity associated with the K protein is reduced by phosphatase treatment, suggesting that the K protein kinase activity is regulated by phosphorylation. The observation that phosphorylation of the K protein is DNA- or RNA-dependent and IL-1-responsive suggests that the function of the K protein is tightly regulated.
authors.affiliation: Department of Medicine, University of Washington, Seattle 98195, USA.
authors.forename: I
authors.initials: I
authors.lastname: Van Seuningen
authors.forename: J
authors.initials: J
authors.lastname: Ostrowski
authors.forename: K
authors.initials: K
authors.lastname: Bomsztyk
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology; D001483:Base Sequence; D002460:Cell Line; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D015151:Immunoblotting; D007375:Interleukin-1 / Q000494:pharmacology*; D051379:Mice; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism; D009838:Oligodeoxyribonucleotides / Q000494:pharmacology*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000302:isolation & purification / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013945:Thymoma; D013953:Thymus Neoplasms; D014407:Tumor Cells, Cultured
chemical_list: D000906:Antibodies; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D007375:Interleukin-1; D016328:NF-kappa B; D009838:Oligodeoxyribonucleotides; D016376:Oligonucleotides, Antisense; D012261:Ribonucleoproteins; D011494:Protein Kinases