title: Sic1 is phosphorylated by CK2 on Ser201 in budding yeast cells.
abstract: We have previously identified Ser201 of Sic1, a yeast cyclin-dependent kinase inhibitor, as an in vitro target of protein kinase CK2. Here we present new evidence, by using specific anti-P-Ser201 antibodies and 2-D gel electrophoresis coupled to MALDI mass spectrometry analysis, that Sic1 is phosphorylated in vivo on Ser201 shortly after its de novo synthesis, during late anaphase in glucose-grown cells. This phosphorylation is also detected in Sic1 immunopurified from G1 cells. In agreement with these data we also show that the catalytic alpha' subunit of CK2, whose function is required for cell cycle progression, is detected in Sic1 immunopurified complexes, and that phosphorylation on Ser201 is reduced after CK2 inactivation at the non-permissive temperature in a cka1delta cka2(ts) yeast strain. These data strongly support the notion that CK2 phosphorylates Sic1 in vivo.
authors.affiliation: Dipartimento di Biotecnologie e Bioscienze, Università degli Studi Milano-Bicocca, P.zza della Scienza 2, 20126 Milano, Italy. paola.coccetti@unimib.it
authors.forename: Paola
authors.initials: P
authors.lastname: Coccetti
authors.forename: Vittoria
authors.initials: V
authors.lastname: Zinzalla
authors.forename: Gabriella
authors.initials: G
authors.lastname: Tedeschi
authors.forename: Gian Luigi
authors.initials: GL
authors.lastname: Russo
authors.forename: Sonia
authors.initials: S
authors.lastname: Fantinato
authors.forename: Oriano
authors.initials: O
authors.lastname: Marin
authors.forename: Lorenzo A
authors.initials: LA
authors.lastname: Pinna
authors.forename: Marco
authors.initials: M
authors.lastname: Vanoni
authors.forename: Lilia
authors.initials: L
authors.lastname: Alberghina
mesh_terms: D000595:Amino Acid Sequence; D047390:Casein Kinase II / Q000378:metabolism*; D020134:Catalytic Domain; D002453:Cell Cycle; D050756:Cyclin-Dependent Kinase Inhibitor Proteins; D008969:Molecular Sequence Data; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism*; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D050756:Cyclin-Dependent Kinase Inhibitor Proteins; C086926:SIC1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D010768:Phosphoserine; D047390:Casein Kinase II