STXBP3 (syntaxin binding protein 3) is a vesicular trafficking protein that regulates intracellular transport and exocytosis. Primary function: STXBP3 participates in insulin-dependent GLUT4 glucose transporter trafficking to the plasma membrane in adipocytes, working alongside STX4 and VAMP2 to mediate vesicle docking and fusion 1. Mechanism: The protein regulates syntaxin-dependent vesicle trafficking and maintains submembrane F-actin networks critical for secretory processes 2. Disease relevance: STXBP3 variants are associated with very early onset inflammatory bowel disease (VEOIBD), bilateral sensorineural hearing loss, and immune dysregulation; loss-of-function mutations impair intestinal epithelial cell polarity and immune function 3. Genetic variants in STXBP3 are linked to incident myocardial infarction, controlling GLUT4 trafficking to plasma membrane 4. STXBP3 expression is elevated in acute allograft rejection and correlates with immunological status 5. Clinical significance: STXBP3 and GOT2 show promising diagnostic potential for early-stage acute allograft rejection 5. STXBP3 genetic variants associate with subcutaneous adipose tissue distribution in HIV-infected patients, linking metabolism and inflammatory pathways 6. The protein interacts with mitochondrial dysfunction pathways relevant to diabetic cardiomyopathy 7.