Characterization of a novel protein inhibitor of protein kinases specific to acidic ribosomal proteins.
The ribosomal stalk composed of acidic P1/P2 proteins and protein P0 is involved directly in the interaction of the elongation factors and mRNAs with the ribosome during protein synthesis. All P proteins are found to be phosphorylated in eucaryotic organisms. In Saccharomyces cerevisiae five different cAMP-independent protein kinases phosphorylating P proteins have been identified and characterized. In contrast to many other protein kinases, relatively little is known about inhibitors of these enzymes. A new protein inhibitor of protein kinases has been purified and characterized. It is a small (18.5 kDa) and acidic (pI = 4.2) protein with high inhibitory potency for PK60S and CK 2. The inhibitor is competitive with respect to protein substrates with Ki values in the range of approximately 6.5 microM for PK60S and approximately 22 microM for CK 2.
Pilecki
M
M
Department of Molecular Biology, Institute of Environmental Protection, Catholic University, Lublin, Poland.
Szyszka
R
R
D004591:Electrophoresis, Polyacrylamide Gel; D005656:Fungal Proteins / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D047428:Protein Kinase Inhibitors; D012269:Ribosomal Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae
D005656:Fungal Proteins; D047428:Protein Kinase Inhibitors; D012269:Ribosomal Proteins