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  • A serine residue in the N-terminal acidic region of rat RPB6, one of the common subunits of RNA polymerases, is exclusively phosphorylated by casein kinase II in vitro.

A serine residue in the N-terminal acidic region of rat RPB6, one of the common subunits of RNA polymerases, is exclusively phosphorylated by casein kinase II in vitro.

Gene (1999-07-07)
K Kayukawa, Y Makino, S Yogosawa, T Tamura
ABSTRACT

RPB6 is one of the common subunits of all eukaryotic RNA polymerases and is indispensable for the enzyme function. Here, we isolated a rat cDNA encoding RPB6. It contained 127 amino acid (a.a.) residues. From alignment of RPB6 homologues of various eukaryotes, we defined two conserved regions, i.e. an N-terminal acidic region and a C-terminal core. In this study, we investigated in vitro phosphorylation of rat RPB6 by casein kinase II (CKII), a pleiotropic regulator of numerous cellular proteins. Three putative CKII-phosphorylated a.a. within rat RPB6 were assigned. We found that serines were phosphorylated by CKII in vitro. Mutagenesis studies provided evidence that a serine at a.a. position 2 was exclusively phosphorylated. Finally, an RPB6-engaged in-gel kinase assay clarified that CKII was a prominent protein kinase in rat liver nuclear extract that phosphorylates RPB6. Therefore, RPB6 was implied to be phosphorylated by CKII in the nucleus. We postulate that the N-terminal acidic region of the RPB6 subunit has some phosphorylation-coupled regulatory functions.

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Anti-POLR2F antibody produced in rabbit, Prestige Antibodies® Powered by Atlas Antibodies, affinity isolated antibody, buffered aqueous glycerol solution