CDK7 phosphorylates serine-5 residues of heptad repeats (consensus YSPTSPS) in the C-terminal domain (CTD) of the large subunit (POLR2A) of RNA polymerase II. Serine-7 residues of the heptad repeats are also phosphorylated at promoters of snRNA genes (Egloff et al. 2007) and CDK7 is required for phosphorylation of serine-7 in vivo (Glover-Cutter et al. 2009). P-TEFb and DNA-PK are able to phosphorylate serine-7 in vitro (Glover-Cutter et al. 2009, Egloff et al. 2010). Impairment of CTD phosphorylation does not appear to affect transcription of snRNA genes but rather impairs 3' processing of the pre-snRNA (Medlin et al. 2003, Jacobs et al. 2004).
Larochelle, S, Shokat, K, Zhang, C, Bentley, DL, Erickson, B, Fisher, RP, Glover-Cutter, K
Uguen, P, Murphy, S, Bentley, DL, Taylor, A, Medlin, JE
Tanzhaus, K, Chapman, RD, Murphy, S, Pitts, L, O'Reilly, D, Eick, D, Egloff, S, Taylor, A
Ogiwara, I, Weiner, AM, Jacobs, EY
Murphy, S, Dienstbier, M, Szczepaniak, SA, Egloff, S, Taylor, A, Knight, S
protein serine/threonine kinase activity of RNA polymerase II (unphosphorylated):Initiation factors at promoter of snRNA gene [nucleoplasm]
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