Transcription factor that specifically binds to the octamer motif (5′-ATTTGCAT-3′) (PubMed:2904654, PubMed:7859290). Regulates IL6 expression in B cells with POU2AF1 (By similarity). Regulates transcription in a number of tissues in addition to activating immunoglobulin gene expression (PubMed:2901913, PubMed:2904654). Modulates transcription transactivation by NR3C1, AR and PGR (PubMed:10480874). ; [Isoform 5]: Activates the U2 small nuclear RNA (snRNA) promoter.