title: Protein kinase CK2 phosphorylates and activates the SR protein-specific kinase 1.
abstract: The serine/arginine subfamily of protein kinases has been conserved throughout evolution and its members are thought to play important roles in the regulation of multiple cellular processes. Mammalian SRPK1 has been considered as a constitutively active kinase that is predominantly expressed in testis. In the present study, recombinant GST-SRPK1 was used as substrate to identify potential protein kinase(s) in testis extracts, involved in phosphorylating and thereby regulating the activity of this enzyme. Using a panel of chromatography media, inhibition by heparin, immunoblot analysis, and phosphopeptide mapping, CK2 was determined to be the major kinase that phosphorylates SRPK1. Phosphorylation of SRPK1 by CK2 occurred mainly at Ser(51) and Ser(555) in vitro, and resulted in approximately 6-fold activation of the enzyme. These findings suggest that SRPK1 may be an important cellular target for CK2 action.
authors.affiliation: Laboratory of Biochemistry, Department of Chemistry, The Aristotelian University of Thessaloniki, Greece.
authors.forename: Ilias
authors.initials: I
authors.lastname: Mylonis
authors.forename: Thomas
authors.initials: T
authors.lastname: Giannakouros
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D047390:Casein Kinase II; D004789:Enzyme Activation; D006367:HeLa Cells; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D016415:Sequence Alignment; D013737:Testis / Q000201:enzymology
chemical_list: C087728:SRPK1 protein, human; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases