Probable E3 ubiquitin protein ligase involved in the proteasome-mediated ubiquitin-dependent degradation of target proteins. Through the degradation of CTNNB1, functions downstream of FOXF2 to negatively regulate the Wnt signaling pathway. Probably plays a role in the development of the central nervous system and in neuronal maintenance (By similarity). Also acts as a transcriptional regulator of genes controlling female reproductive function. May play a role in gene transcription by transactivating GNRH1 promoter and repressing PENK promoter. S-ubiquitinyl-[E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + N(6)-ubiquitinyl-[acceptor protein]-L-lysine. Protein modification; protein ubiquitination. Interacts with CTNNB1. Expressed in the regions of the hypothalamus involved in reproductive control, such as medial preoptic area, arcuate nucleus and ventromedial nucleus. Up-regulated during puberty in the hypothalamus, but not in the cerebral cortex. Belongs to the IRF2BP family.