May play a role in the establisment and maintenance of neuronal transmission and plasticity via its ubiquitin ligase activity. E3 ubiquitin ligases accept ubiquitin from an E2 ubiquitin-conjugating enzyme in the form of a thioester and then directly transfer the ubiquitin to targeted substrates. Highly expressed in the brain, with higher expression during development than in adult. Expressed also in mammary glands, testis, colon and kidney.