Putative transmembrane transporter that plays a role in mitochondrial metabolism via an as yet unclear mechanism (, ). Originally, this mitochondrial protein was thought to act as a proton transmembrane transporter from the mitochondrial intermembrane space into the matrix, causing proton leaks through the inner mitochondrial membrane, thereby uncoupling mitochondrial membrane potential generation from ATP synthesis ( , ). However, this function is controversial and uncoupling may not be the function, or at least not the main function, but rather a consequence of more conventional metabolite transporter activity .
Subcellular locations: Mitochondrion inner membrane
Only in skeletal muscle and heart . Also expressed in white and brown adipose tissues . Is more expressed in glycolytic than in oxidative skeletal muscles.