Calcium signaling in mitochondria is important in order for it to function in response to a variety of extracellular stimuli. Signaling begins with Ca(2+) entry in mitochondria via the Ca(2+) uniporter followed by Ca(2+) activation of three dehydrogenases in the mitochondrial matrix. ARALAR, the neuronal Ca(2+)-binding mitochondrial aspartate-glutamate carrier, has Ca(2+) binding domains facing the extramitochondrial space and functions in the malate-aspartate NADH shuttle (MAS). ARALAR is encoded by the SLC25A12 gene and is expressed in brain and skeletal muscle. ARALAR is required for the synthesis of brain aspartate and N-acetylaspartatemay and plays a role in myelin formation. It is also essential for the transmission of small Ca(2+) signals to mitochondria via an increase in mitochondrial NADH. In addition, ARALAR is implicated in conferring susceptibility to schizophrenia.