STX8 (syntaxin 8) is a t-SNARE protein localized to early endosomes, recycling endosomes, late endosomes, and the trans-Golgi network that mediates vesicle fusion and intracellular protein trafficking 1. As a core component of SNARE complexes, STX8 normally forms functional complexes with VTI1B and VAMP8 to promote endosome fusion 2. STX8 is recycled through retromer-dependent pathways via an evolutionarily conserved IEMeaM sorting motif 3. Clinically, STX8 dysfunction is implicated in multiple pathologies. In cystic fibrosis, STX8 functions as a quality control protein; paradoxically, STX8 knockdown rescues ΔF508-CFTR trafficking to the cell surface by reducing Hsp27-mediated degradation 4. STX8 is essential for cytotoxic T lymphocyte function, regulating lytic granule trafficking and perforin release 5. In renal physiology, STX8 mediates claudin-16 recycling to the plasma membrane, regulating magnesium reabsorption 6. During infection, pathogenic bacteria exploit STX8: Salmonella's SipA effector targets STX8 to maintain its vacuolar niche 7, while Mycobacterium tuberculosis's trehalose dimycolate redirects STX8 from VAMP8 to VAMP2 complexes, inhibiting phagosome maturation 2. In neurodegeneration, STX8 facilitates tau secretion and spreading in Alzheimer's disease and progressive supranuclear palsy 8.