Bacitracin resistance protein (BacA) is a putative undecaprenol kinase. BacA confers resistance to bacitracin, probably by phosphorylation of undecaprenol. More recent studies show that BacA has undecaprenyl pyrophosphate phosphatase activity. Undecaprenyl phosphate is a key lipid intermediate involved in the synthesis of various bacterial cell wall polymers. Bacitracin, a mixture of related cyclic polypeptide antibiotics, is used to treat surface tissue infections. Its primary mode of action is the inhibition of bacterial cell wall synthesis through sequestration of the essential carrier lipid undecaprenyl pyrophosphate, C55-PP, resulting in the loss of cell integrity and lysis. The characteristic phosphatase sequence-motif in this family is likely to be the PGxSRSGG, compared with the PSGH of the PAP family of phosphatases.