E3 ubiquitin-protein ligase which is a component of the N-end rule pathway. Recognizes and binds to proteins bearing specific N-terminal residues that are destabilizing according to the N-end rule, leading to their ubiquitination and subsequent degradation. May be involved in pancreatic homeostasis. Binds leucine and is a negative regulator of the leucine-mTOR signaling pathway, thereby controlling cell growth. S-ubiquitinyl-[E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + N(6)-ubiquitinyl-[acceptor protein]-L-lysine. Protein modification; protein ubiquitination. Interacts with RECQL4. Broadly expressed, with highest levels in skeletal muscle, kidney and pancreas. Present in acinar cells of the pancreas (at protein level). Expressed in fetal pancreas. The RING-H2 zinc finger is an atypical RING finger with a His ligand in place of the fourth Cys of the classical motif. The UBR-type zinc finger forms a pocket that mediates recognition of type 1 N-degrons. It exhibits preference for Arginine in first position, has poor affinity for histidine, and doesn't bind acetylated peptides. The disease is caused by variants affecting the gene represented in this entry. Belongs to the UBR1 family.