Description_x000D_ General description_x000D_ CyclinK is a member of the cyclin family which can regulate transcription through their association with and activation of cyclin-dependent kinases (CDK). The CDK/CyclinK complex can phosphorylate the C-terminal domain (CTD) of the large subunit of RNA polymerase II. CyclinK is associated with potent CTD kinase and CDK kinase activities in vitro and coimmunoprecipitates with POLR2A. CyclinK is a new member of the transcription cyclin family which may play a dual role in regulating CDK and RNA polymerase II activities._x000D_ Physical form_x000D_ Supplied in 50 mM Tris-HCl, pH 7.5, 150 mM NaCl, 10 mM glutathione, 0.1 mM EDTA, 0.25 mM DTT, 0.1 mM PMSF, 25% glycerol._x000D_ Preparation Note_x000D_ After opening, aliquot into smaller quantities and store at -70 °C. Avoid repeating handling and multiple freeze/thaw cycles.