pIEFBPR质粒是一个枯草整合型分泌载体

   ColE1 ori, ColE1 replication origin; amp, ampicillin-resistance marker; spc, spectinomycin-resistance marker; lacI, lac-repressor-encoding gene; Pspac, Pspac promoter; mazF, E.coli toxin gene; Plpp, promoter of E.coli lpp gene; mazE, E.coli antitoxin gene; DR, directly-repeated sequence; amyE-front and amyE-back, upstream and downstream sequences of the B.subtilis amyE gene, respectively; bpr-front and bpr-back, upstream and downstream sequences of the B.subtilis bpr gene, respectively. All of the DNA sequences located between the amyE-front and amyE-back or the bpr-front and bpr-back allow integration into the chromosome of B.subtilis via a double-crossover event, resulting in selection for spectinomycin-resistance. The unique restriction enzyme sites are highlighted in blue.