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Two essential charged
residues that are conserved from Mrp
antiporters to complex I are found in TM5:
L(Glu
144),color magenta;
M(Glu
144), color blue ;N(Glu
133);color yellow;
In the middle of TM7: L(Lys
229),color red; M(Lys
234),color cyan; N(Lys
217),color green, and its e-amino
group points inside the putative proton channel.
Conserved polar residues
in TM12:
L(Lys
399) color green, N(Lys
395) color red lies at the beginning of the
periplasmic half of TM12. It may interact with, and stabilize,
the negatively charged C terminus of TM12a.
Two discontinuous helices -TM7 and TM12 contain a proline that
is conserved between all three antiporter-like subunits: M(Pro
239) in TM7 and M(Pro 399) in TM12；Such helices are likely to
participate in proton or ion transport by introducing some
flexibility and charge to the middle of the membrane.
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