Syntaxin-1A

Syntaxin-1A (STX1A) is a neuronal SNARE protein that plays an essential role in calcium-dependent exocytosis and endocytosis, particularly in neurotransmitter release and hormone secretion (UniProt: Q16623). It functions as part of the SNARE complex alongside SNAP25 and VAMP2, which mediates the fusion of synaptic vesicles with the presynaptic plasma membrane, thereby enabling synaptic transmission. The protein is localized to the plasma membrane of neurons and endocrine cells, where it coordinates membrane fusion events critical for cellular signaling and communication.

STX1A is particularly relevant to synaptic plasticity and neurotransmission pathways, processes that are fundamentally altered in neurodegeneration. While no baseline disease associations are documented in UniProt for this protein, its role in synaptic function makes it relevant to conditions affecting neuronal integrity.

In Alzheimer's Disease, STX1A is downregulated in post-mortem brain tissue compared to age-matched controls, with a mean log2 fold-change of −0.44 (Chaparral AD proteomics). This reduction was detected consistently across 2 of 4 subcellular fractions in a TMT-labeled proteomics experiment, suggesting diminished synaptic vesicle fusion capacity and impaired neurotransmitter release in AD brain, potentially contributing to cognitive dysfunction.