DNA-directed RNA polymerase II subunit GRINL1A (Polr2m)

Isoform 1 seems to be stable part of the Pol II(G) complex form of RNA polymerase II. Pol II synthesizes mRNA precursors and many functional non-coding RNAs and is the fundamental part of the basal RNA polymerase II transcription machinery.

Isoform 1 may play a part in Mediator-dependent regulation of transcription activation. Isoform 1 acts in vitro as negative regulator of transcriptional activation; this repression is relieved from the Mediator complex, which restores Pol II(G) activator-dependent transcription to a level equivalent to that of Pol II (By similarity).