RNA Polymerase II (RNAP II) synthesizes mRNAs and a variety of non-coding RNAs, including snRNAs, snoRNAs, microRNAs, piRNAs and lncRNAs. It comprises 12-13 subunits (13 in D. melanogaster), ten of which form a structurally conserved catalytic core with additional subunits located on the periphery. Notably, five RNAP II subunits are shared with the other two nuclear RNAPs. For transcription initiation, RNAPII assembles with the general transcription factors at promoter DNA to form the pre-initiation complex. (Adapted from FBrf0247389, FBrf0228779, FBrf0213652, PMID:25693126, PMID:23463798 and PMID:17318225.)
Notes on Group
While conventional RNAPII is composed of 12 subunits, RNAPII(G) is a metazoan specific form containing a stoichiometric, tightly associated "Gdown1" (aka POLR2M) subunit. (See FBrf0240009.)
