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Biochem/physiol Actions

The carboxy-terminal repeat domain (CTD) of the largest subunit of RNA pol II contains tandem repeats of a heptapeptide sequence Tyr-Ser-Pro-Thr-Ser-Pro-Ser which is highly conserved among eukaryotic organisms. There are two forms of RNA pol II in vivo, designated IIO, which is extensively phosphorylated at the CTD, and IIA, which is not phosphorylated. The IIA form preferentially enters the pre-initiation complex (PIC), whereas IIO is found in the elongating complex. The kinase activity of TFIIH can mediate CTD phosphorylation, although other kinases, including Cdc2, Ctk1, the Srb10-Srb11 kinase-cyclin pair, and P-TEFb, have also been implicated in CTD phosphorylation. A phosphatase responsible for the dephosphorylation of the CTD has also been identified. CTD phosphatase activity is regulated by TFIIB and TFIIF. The CTD has also been implicated in pre-mRNA processing, most likely functioning as a platform for the recruitment and assembly of factors involved in pre-mRNA processing.

General description

RNA polymerase II (eukaryotic) contains around 10 subunits with a combined molecular weight of 500,000Da. The subunit structure of this enzyme is conserved amongst eukaryotes, and this subunits structure shares similarities with that of RNA pol I and III. The carboxy-terminal repeat domain (CTD) of the largest subunit of RNA pol II contains tandem repeats of a heptapeptide sequence Tyr-Ser-Pro-Thr-Ser-Pro-Ser which is highly conserved among eukaryotic organisms.

Physical form

Clear and colorless frozen liquid solution

Preparation Note

Use a manual defrost freezer and avoid repeated freeze-thaw cycles. While working, please keep sample on ice.