Members of this protein family are the epsilon subunit of malonate decarboxylase. This subunit has malonyl-CoA/dephospho-CoA acyltransferase activity. Malonate decarboxylase may be a soluble enzyme, or linked to membrane subunits and active as a sodium pump. The epsilon subunit is closely related to the malonyl CoA-acyl carrier protein (ACP) transacylase family described by TIGR00128, but acts on an ACP subunit of malonate decarboxylase that has an unusual coenzyme A derivative as its prothetic group.