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Title: It takes two to tango: The dance of the permease
The lactose permease (LacY) of Escherichia coli is the prototype of the major facilitator superfamily, one of the largest families of membrane transport proteins. Structurally, two pseudo-symmetrical six-helix bundles surround a large internal aqueous cavity. Single binding sites for galactoside and H + are positioned at the approximate center of LacY halfway through the membrane at the apex of the internal cavity. These features enable LacY to function by an alternating-access mechanism that can catalyze galactoside/H + symport in either direction across the cytoplasmic membrane. The H + -binding site is fully protonated under physiological conditions, and subsequent sugar binding causes transition of the ternary complex to an occluded intermediate that can open to either side of the membrane. We review the structural and functional evidence that has provided new insight into the mechanism by which LacY achieves active transport against a concentration gradient.  more » « less
Award ID(s):
1747705
PAR ID:
10113185
Author(s) / Creator(s):
;
Date Published:
Journal Name:
The Journal of General Physiology
Volume:
151
Issue:
7
ISSN:
0022-1295
Page Range / eLocation ID:
878 - 886
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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