Interacts with the basal transcription machinery by coordinating the formation of a multiprotein complex at the C-FOS promoter, and linking specific signal responsive activator complexes. Promotes the formation of stable high-order complexes of SRF and PHOX1 and interacts cooperatively with PHOX1 to promote serum-inducible transcription of a reporter gene deriven by the C-FOS serum response element (SRE). Acts as a coregulator for USF1 by binding independently two promoter elements, a pyrimidine-rich initiator (Inr) and an upstream E-box. Required for the formation of functional ARID3A DNA-binding complexes and for activation of immunoglobulin heavy-chain transcription upon B-lymphocyte activation.
Subcellular locations: Cytoplasm, Nucleus
Colocalizes with BTK in the cytoplasm.
Ubiquitous. Isoform 1 is strongly expressed in fetal brain, weakly in adult brain, muscle, and lymphoblasts and is almost undetectable in other adult tissues, while the other isoforms are equally expressed in all adult tissues.