UBQLN2, also known as Ubiquilin-2, is a protein involved in the ubiquitin–proteasome system (UPS), a key pathway for protein degradation in cells. It contains ubiquitin-like (UBL) and ubiquitin-associated (UBA) domains that enable interactions with ubiquitinated proteins and proteasome components. UBQLN2 functions as a shuttle factor, delivering ubiquitinated proteins to the proteasome for degradation and supporting protein quality control.