E3 ubiquitin-protein ligase that acts as a negative regulator of NOD2 signaling by mediating ubiquitination and degradation of RIPK2 (By similarity). Also catalyzes ubiquitination and proteasomal degradation of CANX within the endoplasmic reticulum (By similarity). Could have a role in spermatogenesis (PubMed:10191088). 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 CANX. Expressed exclusively in spermatids (at protein level). Detected in the testis from the postpubertal stage (23 days) onwards, with highest expression at 29 days. The RING-type zinc finger is involved in CANX ubiquitination and degradation, but is not required for interaction with CANX.