AUP1 (D5M9Q) Rabbit mAb #35055

Ancient ubiquitous protein 1 (AUP1) is a component of the ER-associated protein degradation (ERAD) machinery responsible for the ubiquitin-mediated degradation of misfolded proteins (1). AUP1 protein contains four conserved domains, with a long, amino-terminal stretch of hydrophobic amino acids followed by an acyltransferase domain (2). Amino-terminal protein sequences direct localization of AUP1 to both the ER and to cytosolic lipid droplets (3). The AUP1 CUE domain binds ubiquitin (4), while the G2BR domain allows for association between AUP1 and E2 conjugating enzyme UBE2G2 (5,6). The presence of these binding domains suggests a central role for AUP1 in the ubiquitination-mediated protein degradation (2). Research studies indicate that AUP1 recruits UBE2G2 to cytosolic lipid droplets, ER-derived organelles that are sites for storage and hydrolysis of neutral lipids. Inhibition of AUP1 protein function results in decreased ubiquitin-mediated degradation of several proteins, including the cholesterol biosynthetic enzyme HMG-CoA-reductase and the cholesterol synthesis regulator INSIG1 (6).