UBE2D1

UBE2D1 Full Name

ubiquitin-conjugating enzyme E2D 1

UBE2D1 Introduction

Ubiquitin-conjugating enzyme E2D 1 (UBE2D1), also known as UbcH5A, is a member of the highly conserved UbcH5/UBE2D family of E2 ubiquitin-conjugating enzymes that functions as a versatile and promiscuous E2 for a wide range of E3 ubiquitin ligases. Encoded by the UBE2D1 gene on chromosome 10q21.1, UBE2D1 shares approximately 88% amino acid sequence identity with its paralogs UBE2D2 (UbcH5B) and UBE2D3 (UbcH5C), forming a functionally redundant E2 subfamily with broad substrate specificity. Unlike the mitosis-restricted UBE2C, UBE2D enzymes are expressed throughout the cell cycle and participate in diverse ubiquitination processes including protein quality control, inflammatory signaling, and transcriptional regulation.

Figure 1. Strcuture of UBE2D1.

Versatile E2 Activity in Ubiquitin Signaling Networks
UBE2D1 functions with an exceptionally broad range of E3 ligases spanning multiple E3 classes, including RING-type E3s (e.g., MDM2, c-Cbl, TRAF6, CHIP), HECT-type E3s (e.g., Nedd4 family members, E6AP), and U-box E3s (e.g., CHIP). This versatility arises from the structural properties of UBE2D1's E3-binding surface, which accommodates diverse E3 interfaces. With RING E3s, UBE2D1 catalyzes the formation of non-specific polyubiquitin chains (K48-linked for proteasomal degradation; K63-linked for signaling) that are discharged directly onto substrate lysine residues. UBE2D1 is also capable of synthesizing free (unanchored) polyubiquitin chains in cooperation with certain E3 enzymes, which can function as signaling intermediates independent of substrate conjugation. The UbcH5 family is distinguished by the ability to initiate ubiquitin chain synthesis on substrates — a priming activity — which can then be extended by other E2 enzymes including UBE2S and UBE2K. This functional modularity within the ubiquitin conjugation cascade provides cells with remarkable flexibility in generating diverse ubiquitin signals.

UBE2D1 in Inflammatory Signaling, NF-κB Regulation, and Cancer
UBE2D1/UBE2D2/UBE2D3 are essential mediators of pro-inflammatory signaling through their role in the ubiquitin-dependent activation of the NF-κB pathway. UBE2D enzymes function with the E3 ligase TRAF6 to catalyze K63-linked polyubiquitination of TRAF6 itself and downstream targets including NEMO (IKKγ), a critical step in the assembly of the IKK complex and subsequent NF-κB activation. UBE2D family members also cooperate with the E3 ligase cIAP1/2 in TNF receptor signaling complexes. In cancer, the UBE2D family contributes to the degradation of the tumor suppressor p53 through cooperation with MDM2 (and MDM2 homolog MDMX), promoting p53 polyubiquitination and proteasomal turnover. Elevated UBE2D1 expression has been reported in breast cancer and hepatocellular carcinoma, where it is associated with reduced p53 levels and enhanced proliferation. The functional redundancy among UBE2D family members complicates targeted therapeutic strategies, as selective inhibition of a single paralog may be compensated by the others. Pan-UbcH5 inhibitors are being explored preclinically to simultaneously block NF-κB signaling and restore p53 function in cancer cells.

Alternate Names for UBE2D1

UBE2D1; ubiquitin-conjugating enzyme E2D 1; SFT; UBCH5; UBC4/5; UBCH5A; E2(17)KB1; ubiquitin-conjugating enzyme E2 D1; UBC4/5 homolog; stimulator of Fe transport