Ab

polymerase

4H8

recognizes both the phosphorylated and unphosphorylated forms of the largest subunit of RNA pol II

phospho Ser2

RNA pol II phosphorylated at serine 2 is enriched over the gene body and is associated with transcriptional elongation

phospho Ser5

RNA pol II Serine 5 phosphorylation is confined to promoter regions and is necessary for the initiation of transcription.