Serine beta-lactamase-like protein LACTB, mitochondrial is an enzyme that in humans is encoded by the LACTB gene. This gene encodes a 54 kDa protein sharing significant 
sequence similarity to serine proteases of the penicillin binding protein and beta-lactamase superfamily occurring in bacteria.
 It is involved in the regulation of the metabolic circuitry. A causal association has been found between LACTB and obesity. In breast cancer, LACTB has a tumor suppressor function by modulating lipid metabolism.