Accumulation of MraY proteins. Membranes from induced cultures bearing no plasmid (lane 1), pBAD30 (lane 2), or pBAD30 carrying the indicated allele of EcmraY (lanes 3–7) were analyzed by immunoblot with antibodies raised against a peptide of MraY. The position of molecular mass standards are indicated to the left and the relative amount of MraY, by integration of the band indicated by an asterisk, is given at the bottom of lanes 4–7, relative to the amount in lane 3.