It takes two to tango: The dance of the permease.

ABSTRACT: 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

SUBMITTER: Kaback HR 

PROVIDER: S-EPMC6605686 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature