E3 ubiquitin-protein ligase that is essential for proper development of the forebrain, the eye, and the face. Catalyzes monoubiquitination of serine/threonine-protein phosphatase 2A (PP2A) catalytic subunit PPP2CA/PPP2CB (By similarity). Negatively regulates nitric oxide production by inducing NOS1 and NOS3 translocation to actin cytoskeleton and inhibiting their enzymatic activity (By similarity). 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. Interacts with NOS1 and NOS3 (By similarity). Interacts with PP2A holoenzyme, containing PPP2CA, PPP2CB, PPP2R1A and PPP2R2A subunits (By similarity). Translocates from nucleus to cytoplasm in the G2 phase of the cell cycle. The U-box-like region is a truncated U-box domain. It is unknown whether it is functional or not. Belongs to the NOSIP family.