Multifunctional transcription factor with different regions mediating its different effects (PubMed:10640682). Acts by binding (via its C-terminal domain) to sequences related to the consensus octamer motif 5'-ATGCAAAT-3' in the regulatory regions of its target genes. Regulates the expression of specific genes involved in differentiation and survival within a subset of neuronal lineages (PubMed:11053412). It has been shown that activation of some of these genes requires its N-terminal domain, maybe through a neuronal-specific cofactor. Ativates BCL2 expression and protects neuronal cells from apoptosis (via the N-terminal domain). Induces neuronal process outgrowth and the coordinate expression of genes encoding synaptic proteins. Exerts its major developmental effects in somatosensory neurons and in brainstem nuclei involved in motor control. Stimulates the binding affinity of the nuclear estrogene receptor ESR1 to DNA estrogen response element (ERE), and hence modulates ESR1-induced transcriptional activity. May positively regulate POU4F2 and POU4F3. Regulates dorsal root ganglion sensory neuron specification and axonal projection into the spinal cord. Plays a role in TNFSF11-mediated terminal osteoclast differentiation. Negatively regulates its own expression interacting directly with a highly conserved autoregulatory domain surrounding the transcription initiation site (By similarity). Able to act as transcription factor, cannot regulate the expression of the same subset of genes than isoform 1. Does not have anitapoptotic effect on neuronal cells. Interacts (via N-terminus) with RIT2; the interaction controls POU4F1 transactivation activity on some neuronal target genes. Isoform 1 interacts with POU4F2; this interaction inhibits both POU4F1 DNA-binding and transcriptional activities. Isoform 1 interacts (C-terminus) with ESR1 (via DNA-binding domain); this interaction decreases the estrogen receptor ESR1 transcriptional activity in a DNA- and ligand 17-beta-estradiol-independent manner. Detected in brain, spinal cord and dorsal root ganglion (PubMed:2739723, PubMed:8835784). Isoform 2 is detected in brain, spinal cord, dorsal root ganglion and spleen (PubMed:8835784). The C-terminal domain is able to act as both DNA-binding domain and a transcriptional activator. The N-terminal domain is also required for transactivation activity on some target genes acting as a discrete activation domain. Neurite outgrowth and expression of genes required for synapse formation are primarily dependent on the C-terminal domain, however the N-terminal domain is required for maximal induction. Belongs to the POU transcription factor family. Class-4 subfamily.