title: Casein kinases phosphorylate multiple residues spanning the entire hnRNP K length.
abstract: Heterogeneous Nuclear Ribonucleoprotein K (hnRNP K) is an RNA/DNA-binding protein involved in many processes that regulate gene expression. K protein's pleiotropic action reflects the diversity of its molecular interactions. Many of these interactions have been shown to be regulated by phosphorylation. K protein contains more than seventy potential phosphorylation sites. We used an integrated approach of mass spectrometry and computer analysis to explore patterns of K protein phosphorylation. We found that in vitro a single kinase can phosphorylate K protein on multiple sites spanning the entire length of the protein, including residues contained within the RNA/DNA-binding domains. 2-D gel electrophoresis of K protein purified from cells identified 5-8 spots. Mass spectrometry of K protein isolated from proliferating cells and from cells under oxidative stress revealed the same pattern of phosphopeptides. The structural implications of phosphorylation are discussed.
authors.affiliation: Institute of Oncology, 02-781 Warsaw, Poland.
authors.forename: Michał
authors.initials: M
authors.lastname: Mikula
authors.forename: Jakub
authors.initials: J
authors.lastname: Karczmarski
authors.forename: Artur
authors.initials: A
authors.lastname: Dzwonek
authors.forename: Tymon
authors.initials: T
authors.lastname: Rubel
authors.forename: Ewa
authors.initials: E
authors.lastname: Hennig
authors.forename: Michał
authors.initials: M
authors.lastname: Dadlez
authors.forename: Janusz M
authors.initials: JM
authors.lastname: Bujnicki
authors.forename: Karol
authors.initials: K
authors.lastname: Bomsztyk
authors.forename: Jerzy
authors.initials: J
authors.lastname: Ostrowski
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D047388:Casein Kinases / Q000737:chemistry*; D034641:Heterogeneous-Nuclear Ribonucleoprotein K / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011487:Protein Conformation; D051381:Rats
chemical_list: D034641:Heterogeneous-Nuclear Ribonucleoprotein K; D047388:Casein Kinases