Calcium homeostasis modulator 1 (CALHM1) is a pore-forming subunit of a voltage-gated ion channel and a voltage-gated ATP channel that in humans is encoded by the CALHM1 gene.[5][6]
CALHM1 was identified by a tissue-specific gene expression profiling approach[7] that screened for genes located on susceptibility loci for late-onset Alzheimer's disease (AD) and that are preferentially expressed in the hippocampus,[5] a brain region affected early in AD. CALHM1 is a plasma membrane calcium-permeable ion channel regulated by voltage and extracellular calcium levels.[8] The exact function of CALHM1 in the brain is not completely understood, but studies have shown that CALHM1 controls neuronal intracellular calcium homeostasis and signaling, as well as calcium-dependent neuronal excitability and memory in mouse models.[8][9][10] Recent data have also shown that CALHM1 might facilitate the proteolytic degradation of the cerebral amyloid beta peptide, a culprit in AD pathogenesis.[11]
CALHM1 is expressed in taste bud cells where it controls purinergic receptor-mediated taste transduction in the gustatory system.[12][13]