Description
The integral membrane protein MadBfrom the anaerobic bacterium Malonomonas rubra is a component of the multienzyme complex EC 4.1.1.89, biotin-dependent malonate decarboxylase. The free energy of the decarboxylation reaction is used to pump Na+ out of the cell. The enzyme is a member of the Na+-translocating decarboxylase family, other members of which include EC 4.1.1.3 (oxaloacetate decarboxylase) and EC 4.1.1.41 (methylmalonyl-CoA decarboxylase)