ubch-2

UBE2H is a member of the ubiquitin-conjugating E2 family whose members perform the second step in the ubiquitination reaction. Initially identified as the main process for protein degradation, ubiquitination is believed nowadays to be crucial for a wider range of cellular processes. The outcome of the ubiquitin-conjugation reaction, and thereby the fate of the substrate, is heavily dependent on the number of ubiquitin molecules attached and how these ubiquitin molecules are inter-connected. To deal with this complexity and to allow adequate ubiquitination in time and space, a highly sophisticated conjugation machinery has been developed. In a sequential manner, ubiquitin becomes activated by a ubiquitin-activating enzyme (E1), which then transfers the ubiquitin to a group of ubiquitin-conjugating enzymes (E2s). Next, ubiquitin-loaded E2s are interacting with ubiquitin-protein ligases (E3s) and ubiquitin is conjugated to substrates on recruitment by the E3. These three key enzymes are operating in a hierarchical system, wherein two E1s and 35 E2s have been found and hundreds of E3s have been identified in humans.

Ubiquitin-Conjugating Enzyme E2 H (UBE2H) belongs to the E2 Ubiquitin-Conjugating Enzyme family. The modification of proteins with ubiquitin is an important cellular mechanism for targeting abnormal or short-lived proteins for degradation. Ubiquitination involves at least three classes of enzymes: ubiquitin-activating enzymes, or E1s, ubiquitin-conjugating enzymes, or E2s, and ubiquitin-protein ligases, or E3s. It has been shown to conjugate ubiquitin to histone H2A in an E3 dependent manner in vitro. UBE2H is the human homolog to the yeast DNA repair gene RAD6, which is induced by DNA damaging reagents. UBE2H has been associated with cancer-induced cachexia and with the regulation of sepsis-induced muscle proteolysis.