Syntaxin-binding protein 5

Syntaxin-binding protein 5 (STXBP5) is a regulatory protein that modulates calcium-dependent exocytosis and neurotransmitter release by inhibiting membrane fusion between transport vesicles and the plasma membrane. It may regulate trans-SNARE complex assembly and compete with STXBP1 for STX1 binding, thereby controlling vesicular trafficking processes critical to neuronal communication (UniProt: Q5T5C0).

STXBP5 functions in synaptic transmission pathways and is expressed in neuronal tissues where vesicular release occurs. UniProt records no primary disease associations for this protein.

In Alzheimer's disease, STXBP5 shows ambiguous regulation across brain subcellular fractions. Analysis of post-mortem AD brain tissue versus age-matched controls using TMT-labeled proteomics across four fractions (P2, P3, S2, S3) revealed a mean log2 fold-change of −0.33, indicating modest overall reduction (Chaparral AD proteomics). The ambiguous direction classification suggests differential regulation depending on subcellular compartment, warranting further investigation of its role in AD pathophysiology.