Details of a model of the oxalate transporter of Oxalobacter formigenes (OxlT). The helices are colored in groups to reflect the 4-fold symmetry of the 12 TM helix bundle. Green helices are peripheral, yellow and magenta helices line the translocation pathway. The model was developed by application of a new method for orienting TM domains in electron density maps. The method correctly predicted the relative orientation of TM2 and TM11 in OxlT, as indicated by the predicted positions of the residues detailed in the figure, which had been shown from crosslinking experiments to reside at the interface of TM2 and TM11. Residue K355 has been implicated in binding of the oxalate substrate. For details, see Beuming and Weinstein, pages 119–125.
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