VIPAS39 is a vesicular trafficking protein that functions as a key regulator of endosomal maturation and epithelial cell polarity. Primary function: VIPAS39 interacts with VPS33B to facilitate endosomal maturation and participates in the apical RAB11A-dependent recycling pathway in epithelial cells, critical for maintaining apical-basolateral polarity 1. It also functions independently of VPS33B in lysosomal trafficking through association with the HOPS complex 2. Mechanism: VIPAS39 serves as a SNARE-interacting component of the FERARI tethering complex, coordinating Rab11-dependent endocytic recycling at sorting endosomes 3. Additionally, VIPAS39 regulates protein sorting into late endosomes and exosomal export pathways 4. Disease relevance: Pathogenic VIPAS39 mutations cause arthrogryposis, renal dysfunction, and cholestasis (ARC) syndrome 2, an autosomal recessive disorder affecting endosomal trafficking 5. Clinical significance: VIPAS39 represents an emerging therapeutic target; its inhibition overcomes ferroptosis resistance in epithelial ovarian cancer by preventing ACSL4 exosomal export 4. VIPAS39 also displays favorable neuropsychiatric profiles in alcohol-related phenotypes 6, suggesting broader therapeutic applications beyond traditional trafficking disorders.