Trans-2-Enoyl-CoA Reductase Mitochondrial (MECR) belongs to the zinc-containing alcohol dehydrogenase family. MECR localizes to the mitochondrion. It is highly expressed in skeletal and heart muscle and expressed at lower levels in the placenta, liver, kidney and pancreas, with weakly or no expression in the lung. MECR exists as a homodimer, which catalyzes the reduction of trans-2-enoyl-CoA to acyl-CoA with chain length from C6 to C16 in an NADPH-dependent manner with preference to medium chain length substrate. MECR may take part in the mitochondrial synthesis of fatty acids.