Essential for high-level bacitracin resistance (PubMed:15388429). Part of the ABC transporter complex BcrAB. Probably responsible for the translocation of the substrate across the membrane (Probable). The complex is probably composed of two ATP-binding proteins (BcrA) and two transmembrane proteins (BcrB). Transcription is activated by the regulatory protein BcrR in the presence of bacitracin. Disruption mutant is sensitive to bacitracin.