Disruption of this mechanism interfered with the expression of two growth-factor-induced genes regulated by polymerase pausing, but did not influence expression or polymerase occupancy at two non-paused genes [ residues, and thus the potential for RPB1 CTD acetylation, arose with animal multicellularity during an expansion in the overall number of CTD repeats in Metazoa.Our phylogenetic analysis further showed that p300/KAT3B, the acetyltransferase that modifies the RPB1 CTD, was present at the appearance K-containing repeats.However, in spite of our increasing knowledge of these marks, the full number and identity of repeats that undergo modification during transcription are unknown.The CTD repeat motif and tandem repeat orientation are observed in most eukaryotic model organisms, and this configuration evolved early in the history of eukaryotes .Conserved heptad repeats are found in the linker-proximal part of the mammalian CTD, but the sequence of the distal heptad repeats, which are not present in yeast, diverge from this consensus sequence.Eight of the non-consensus repeats in human and mouse CTDs carry a lysine at position 7 (K The human RNA polymerase II subunit 1 (RPB1) C-terminal domain (CTD) contains more heptad repeats than the yeasts, and eight of its non-consensus distal repeats have a lysine residue.
The enzyme is composed of 12 subunits (RPB1–12), five of which are shared among the three eukaryotic polymerase complexes.
These results are in agreement with an extensive study of CTD repeat number and content that appeared while this manuscript was in preparation [).
Overall, the seventh position of the heptad repeat is the most variable, but different clades exhibit different patterns of variation.
content of the CTD expanded in specific developmentally complex metazoan lineages.
The functional analysis of genes regulated by ac RPB1 highlight functions involved in the origin of and diversification of complex Metazoa.
The largest subunit, called RPB1, is unique to RNA polymerase II and is involved in its catalytic activity.