LTN1 (listerin E3 ubiquitin protein ligase 1) is a core E3 ubiquitin ligase component of the ribosome-associated quality control (RQC) complex, a surveillance mechanism that eliminates incomplete nascent polypeptides produced during translation stalling 1. Within RQC, LTN1 is recruited to obstructed ribosomal subunits by NEMF and mediates ubiquitination of stalled nascent chains 2. This ubiquitination targets substrates for VCP/p97-dependent extraction and proteasomal degradation 1. Beyond canonical cytoplasmic RQC, LTN1 operates at the endoplasmic reticulum and mitochondria 1. Recently, LTN1 has been shown to suppress RAN (repeat-associated non-AUG) translation from GC-rich repeats, with depletion markedly increasing toxic RAN products from C9ORF72 and FMR1 repeats implicated in neurodegeneration 3. Additionally, LTN1 recruits TRIM27 to ubiquitinate RIG-I-like receptors for ESCRT-dependent degradation, negatively regulating antiviral innate immunity 4. LTN1 mutations cause neurodegeneration in mice, and RQC defects impair cellular fitness 12, highlighting LTN1's critical role in protein quality control and disease prevention.