Transcription factor that specifically binds to the octamer motif (5'-ATTTGCAT-3'). Regulates transcription in a number of tissues in addition to activating immunoglobulin gene expression. Modulates transcription transactivation by NR3C1, AR and PGR. Isoform 5 activates the U2 small nuclear RNA (snRNA) promoter. Belongs to the POU transcription factor family. Class- 2 subfamily. 5 isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.