Ring Finger Protein 125 (RNF125)

E3 ubiquitin-protein ligase RNF125 is a protein may function as a positive regulator in the T-cell receptor signaling pathway.The 232-amino acid protein contains an N-terminal RING finger domain. RT-PCR analysis detected highest expression in bone marrow, spleen, and thymus, with weak to moderate expression in most other tissues examined. Expression was much higher in T cells than in B cells.

However, functional and Western blot analyses showed that TRAC1 had E3 activity in the presence of UBC4 (UBE2D2), UBCH5C (UBE2D3), or UBC13 (UBE2N)/UEV1A (UBE2V1), but not UBCH7. Mutation analysis confirmed that the E3 ubiquitin ligase activity of TRAC1 was dependent on an intact RING finger, but it did not require the C terminus.