Amyloid-beta A4 precursor protein-binding family A member 1

APBA1 (amyloid-beta A4 precursor protein-binding family A member 1) is a 837-amino acid protein that functions in synaptic vesicle exocytosis by binding Munc18-1, a core component of the synaptic release machinery (UniProt: Q02410). It also modulates amyloid-beta precursor protein (APP) processing and participates in the LIN-10–LIN-2–LIN-7 complex, which associates with motor protein KIF17 to transport NMDA receptor-containing vesicles along microtubules.

APBA1 is primarily relevant to synaptic function and vesicular transport in the nervous system. The protein interacts with key elements of both exocytic and endosomal trafficking pathways, positioning it at the intersection of synaptic transmission and amyloid metabolism.

APBA1 is significantly downregulated in Alzheimer's disease brain tissue compared to age-matched controls (Chaparral AD proteomics). Quantitative proteomic analysis detected a mean log2 fold-change of −0.55 in post-mortem human AD brain across subcellular fractions, suggesting reduced protein abundance in the disease state. This downregulation may contribute to impaired synaptic function and altered APP processing observed in AD pathology.