N. Fong et Dl. Bentley, Capping, splicing, and 3 ' processing are independently stimulated by RNA polymerase II: different functions for different segments of the CTD, GENE DEV, 15(14), 2001, pp. 1783-1795
Capping, splicing, and cleavage/polyadenylation of pre-mRNAs are interdepen
dent events that are all stimulated in vivo by the carboxy-terminal domain
(CTD) of RNA Pol II. We show that the CTD independently enhances splicing a
nd 3 ' processing and that stimulation of splicing by enhancers is facilita
ted by the CTD. We provide evidence that stimulation of 3 ' processing by t
he CTD requires contact with the 50-kD subunit of the cleavage stimulation
factor, CstF. Overexpression of the CTD-binding domain of CstF p50 had a do
minant-negative effect on 3 ' processing without disrupting the CstF comple
x. The CTD comprises 52 heptad repeats. The CTD carboxyl terminus including
heptads 27-52 supported capping, splicing, and 3 ' processing but the amin
o terminus supported only capping. We conclude that the CTD independently s
timulates ail three major pre-mRNA processing steps and that different regi
ons of the CTD can serve distinct functions in pre-mRNA processing.