Has acyl-CoA thioesterase activity towards medium and long-chain (C14 to C18) fatty acyl-CoA substrates, and probably plays a role in mitochondrial fatty acid metabolism (By similarity). Plays a role in the apoptotic process, possibly via its regulation of AKT1 activity (PubMed:19421406). H2O + hexadecanoyl-CoA = CoA + H(+) + hexadecanoate H2O + octanoyl-CoA = CoA + H(+) + octanoate decanoyl-CoA + H2O = CoA + decanoate + H(+) dodecanoyl-CoA + H2O = CoA + dodecanoate + H(+) H2O + tetradecanoyl-CoA = CoA + H(+) + tetradecanoate (9Z)-octadecenoyl-CoA + H2O = (9Z)-octadecenoate + CoA + H(+) (5Z,8Z,11Z,14Z)-eicosatetraenoyl-CoA + H2O = (5Z,8Z,11Z,14Z)-eicosatetraenoate + CoA + H(+) Homodimer and homotetramer (By similarity). Interacts with AKT1 in the cytosol (PubMed:11598301). (Microbial infection) Interacts with V-AKT from AKT8 murine leukemia virus. Released from the mitochondria into the cytosol in response to apoptotic stimuli. Phosphorylated. No visible phenotype. Mice have abnormally elongated mitochondria, but mitochondrial function appears to be normal. Belongs to the THEM4/THEM5 thioesterase family. Contaminating sequence. Potential poly-A sequence. Contaminating sequence. Potential poly-A sequence. Contaminating sequence. Potential poly-A sequence.