VAPA (Vesicle-associated Membrane Protein-associated Protein A) is a ubiquitously expressed protein involved in intracellular membrane trafficking, lipid transport, and the regulation of endoplasmic reticulum (ER)-plasma membrane contact sites. It forms heterodimers with its homolog VAPB, anchoring to ER membranes via a C-terminal transmembrane domain. The N-terminal MSP (major sperm protein) domain of VAPA interacts with FFAT (two phenylalanines in an acidic tract) motif-containing proteins, facilitating lipid exchange and organelle crosstalk. VAPA plays critical roles in maintaining ER structure, coordinating vesicular transport, and modulating lipid metabolism.
Antibodies targeting VAPA are essential tools for studying its localization, protein interactions, and functions in cellular processes. They are widely used in techniques like immunofluorescence, Western blotting, and co-immunoprecipitation to investigate VAPA’s involvement in neurodegenerative diseases (e.g., ALS), cancer (e.g., lipid signaling in tumor progression), and metabolic disorders. Dysregulation of VAPA has been linked to disrupted lipid homeostasis and ER stress, making it a potential biomarker or therapeutic target. Commercial VAPA antibodies are typically validated for specificity against human, mouse, or rat isoforms, though cross-reactivity challenges may arise due to high homology with VAPB. Recent studies also explore VAPA’s role in viral pathogenesis, as some pathogens exploit ER-membrane contact sites for replication.