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. Author manuscript; available in PMC: 2007 Oct 15.
Published in final edited form as: J Struct Biol. 2006 Dec 24;158(3):494–502. doi: 10.1016/j.jsb.2006.12.004

Figure 1.

Figure 1

A ribbon representation of the crystal structure of AcrB showing three AcrB protomers that constitute the symmetric trimer of the transporter in R32 space group. The vestibular opening is located in the center just above the outer leaflet of the inner membrane in the periplasm that allows ligands from the periplasm to enter the inner central cavity. The top of the inner central cavity leads to the pore in the pore domain which then opens out into a funnel in the TolC docking domain for conveying the captured molecules to the TolC protein spanning the outer membrane and then ejects the substrates to the external medium. The bottom of the tripartite AcrB assembly extends into the cytoplasm which may allow the direct capture of toxic substrates from the cytosol through the central opening of the trimer cytoplasmic face.