transcription by RNA polymerase II obsolete phosphorylation of RNA polymerase II C-terminal domain serine 2 residues true GO:0071619 OBSOLETE. The process of introducing a phosphate group onto a serine residue at position 2 within the heptapeptide repeat (YSPTSPS) of the C-terminal domain of RNA polymerase II. Typically, phosphorylation of serine 2 (Ser2) occurs subsequent to phosphorylation of serine 5 and is thus seen in the middle and 3' ends of genes. In vivo, Ser2 phosphorylation is primarily performed by CTDK-I in S. cerevisiae or CDK9 in metazoans. 2010-02-09T02:37:02Z mah This term was obsoleted because it represents a molecular function. biological_process