VPS39 is a key subunit of the HOPS (homotypic fusion and protein sorting) complex that plays critical roles in vesicle-mediated protein trafficking to lysosomal compartments 1. The protein functions as a tethering factor that mediates membrane fusion events between late endosomes and lysosomes, as well as autophagosome-lysosome fusion 2. VPS39 regulates autophagy flux by facilitating the recruitment of the HOPS complex to Rab7-positive late endosomes and controlling autolysosome formation 3. The protein's dysfunction has significant disease relevance, particularly in type 2 diabetes, where VPS39 deficiency impairs muscle stem cell differentiation through altered autophagy and epigenetic programming 4. Additionally, VPS39 acts as a negative regulator of primary cilia formation by controlling autophagy-mediated processes 5. Clinically, VPS39 represents a potential therapeutic target, as evidenced by its interaction with viral proteins during SARS-CoV-2 infection 6 and African swine fever virus replication 7. The protein also exists in multiple isoforms, with hVps39-2/TRAP1 serving as a Rab5 effector in endosomal trafficking 8, highlighting its diverse roles in cellular membrane dynamics and disease pathogenesis.