Catalysis of the reaction: nucleoside triphosphate + RNA(n) = diphosphate + RNA(n+1). Utilizes a DNA template that contains an RNA polymerase II specific promoter to direct initiation and catalyses DNA-template-directed extension of the 3'-end of an RNA strand by one nucleotide at a time. Can initiate a chain 'de novo'.
Synonyms:
exact_synonym:
DNA-directed RNA polymerase activity involved in transcription from RNA polymerase II promoter
xref:
reactome:R-HSA-6814549 "Pre-snRNA transcript initiation, Integrator binding, LEC binding"; reactome:R-HSA-6814559 "Pre-snRNA is elongated and capped with 7-methylguanosine"