Budding and fission yeast casein kinase I isoforms have dual-specificity protein kinase activity.

Abstract

We have examined the activity and substrate specificity of the Saccharomyces cerevisiae Hrr25p and the Schizosaccharomyces pombe Hhpl, Hhp2, and Ckil protein kinase isoforms. These four gene products are isotypes of casein kinase I (CKI), and the sequence of these protein kinases predicts that they are protein serine/threonine kinases. However, each of these four protein kinases, when expressed in Escherichia coli in an active form, was recognized by anti-phosphotyrosine antibodies. Phosphoamino acid analysis of 32P-labeled proteins showed phosphorylation on serine, threonine, and tyrosine residues. The E. coli produced forms of Hhpl, Hhp2, and Ckil were autophosphorylated on tyrosine, and both Hhpl and Hhp2 were capable of phosphorylating the tyrosine-protein kinase synthetic peptide substrate polymer poly-E4Yl. Immune complex protein kinases assays from S. pombe cells showed that Hhpl-containing precipitates were associated with a protein-tyrosine kinase activity, and the Hhpl present in these immunoprecipitates was phosphorylated on tyrosine residues. Although dephosphorylation of Hhpl and Hhp2 by Ser/Thr phosphatase had little effect on the specific activity, tyrosine dephosphorylation of Hhpl and Hhp2 caused a 1.8-to 3.1-fold increase in the Km for poly-E4Y, and casein. These data demonstrate that four different CKI isoforms from two different yeasts are capable of protein-tyrosine kinase activity and encode dual-specificity protein kinases.

Casein Kinase 1 Is Tightly Associated with Paired‐Helical Filaments Isolated from Alzheimer's Disease Brain

“…Initial velocity measurements were carried out in duplicate under these conditions with ATP (4,8,16,20,26,and 37.5 tiM) as the varied substrate. Kinetic constants and their standard errors were calculated as by Hoekstra et al (1994). For assay of inhibitor potency, [y-32P]ATP was held constant (10 1.sM) and the inhibitor CKI7 (Chijiwa et al, 1989) was varied (2,4, 8, 16, and 32 1.tM).…”

PML enhances the regulation of p53 by CK1 in response to DNA damage

“…A CK1-related kinase in yeast, hrr25, is essential for DNA repair and can be complemented by its mammalian homologs CK1d and e isoforms (Hoekstra et al, 1994). p53 is a substrate for both isoforms, linking them to DNA repair and cell-cycle regulation also in mammalian cells (Knippschild et al, 1997).…”

The Recombinant α Isoform of Protein Kinase CK1 from Xenopus laevis can Phosphorylate Tyrosine in Synthetic Substrates

“…Further evidence that links CKI to the process of cell division is provided by the immunocytological studies that localized CK1 to centrosomes and cytosol vesicles during interphase but to kinetochores and mitotic spindles during mitosis (Brockman et al, 1992). A possible negative regulation by phosphorylation of the carboxyl end of the larger isoforms of yeast (Hoekstra et al, 1994) and mammals (Graves and Roach,195)s) has been reported. Developmental regulation of the expression and possible activation by y radiation of an a isoform isolated from Drosophila has also been recently described (Santos et al, 1996).…”

“…In Saccharomyces cerevisiae, and in S. pombe, four different genes have been described and studied (Hoekstra et al, 1994).…”

“…More recently, a surprising finding has been reported (Hoekstra et al, 1994), indicating that some, but not all, yeast CK1 isoforms can phosphorylate tyrosine residues in poly (Glu'" :…”