Specific protein kinase from Saccharomyces cerevisiae cells phosphorylating 60S ribosomal proteins.
A protein kinase, specific for 60S ribosomal proteins, has been isolated from Saccharomyces cerevisiae cells, purified to almost homogeneity and characterized. The isolated enzyme is not related to other known protein kinases. Enzyme purification comprised three chromatography steps; DEAE-cellulose, phosphocellulose and heparin-Sepharose. SDS/PAGE analysis of the purified enzyme, indicated a molecular mass of around 71 kDa for the stained single protein band. The specific activity of the protein kinase was directed towards the 60S ribosomal proteins L44, L44', L45 and a 38 kDa protein. All the proteins are phosphorylated only at the serine residues. None of the 40S ribosomal proteins were phosphorylated in the presence of the kinase. For that reason we have named the enzyme the 60S kinase. An analysis of the phosphopeptide maps of acidic ribosomal proteins, phosphorylated at either the 60S kinase or casein kinase II, showed almost identical patterns. Using the immunoblotting technique, the presence of the kinase has been detected in extracts obtained from intensively growing cells. These findings suggest an important role played by the 60S kinase in the regulation of ribosomal activity during protein synthesis.
Pilecki
M
M
Department of Molecular Biology, Maria Curie-Skłodowska University, Lublin, Poland.
Grankowski
N
N
Jacobs
J
J
Gasior
E
E
D002846:Chromatography, Affinity; D002848:Chromatography, DEAE-Cellulose; D002852:Chromatography, Ion Exchange; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D015151:Immunoblotting; D007074:Immunoglobulin G; D007700:Kinetics; D008970:Molecular Weight; D010449:Peptide Mapping; D010748:Phosphopeptides / Q000302:isolation & purification; D010766:Phosphorylation; D011494:Protein Kinases / Q000302:isolation & purification* / Q000378:metabolism*; D038601:Ribosomal Protein S6; D019893:Ribosomal Protein S6 Kinases; D012269:Ribosomal Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000254:growth & development; D013379:Substrate Specificity
D007074:Immunoglobulin G; D010748:Phosphopeptides; D038601:Ribosomal Protein S6; D012269:Ribosomal Proteins; D011494:Protein Kinases; D019893:Ribosomal Protein S6 Kinases