Background of the antigen
CALHM1 is a 346 amino acid multi-pass endoplasmic reticulum membrane protein that belongs to the FAM26 family. CALHM1 co-localizes with GRP 78 to the endoplasmic reticulum. Predominantly expressed in adult brain, CALHM1 may be a pore-forming ion channel that controls cytosolic Ca2+ permeability and cytosolic Ca2+ concentration in the cell. It is suggested that CALHM1 regulates amyloid precursor protein proteolysis and aggregated amyloid-beta peptides levels in a Ca2+ dependent manner. CALHM1 homomultimerizes and shares strong sequence similarities with the selectivity filter of the NMDA receptor, which generates a large Ca2+ conductance across the plasma membrane. CALHM1 may be a potential factor involved in the pathogenesis of Alzheimer's disease.