Isoform 1 appears to be a stable component of the Pol II(G) complex form of RNA polymerase II (Pol II). Pol II synthesizes mRNA precursors and many functional non-coding RNAs and is the central component of the basal RNA polymerase II transcription machinery. Isoform 1 may play a role in the Mediator complex-dependent regulation of transcription activation. Isoform 1 acts in vitro as a negative regulator of transcriptional activation; this repression is relieved by the Mediator complex, which restores Pol II(G) activator-dependent transcription to a level equivalent to that of Pol II.
Subcellular locations: Nucleus
Detected in adult an fetal brain. Detected in heart, kidney, skeletal muscle, small intestine, lung, prostate and testis.