TY  - JOUR
A1  - Dempski, Robert E.
A1  - Hartung, Klaus
A1  - Friedrich, Thomas
A1  - Bamberg, Ernst
T1  - Fluorometric measurements of intermolecular distances between the α- and β-Subunits of the Na+/K+-ATPase
T2  - Journal of biological chemistry
N2  - The Na+/K+-ATPase maintains the physiological Na+ and K+ gradients across the plasma membrane in most animal cells. The functional unit of the ion pump is comprised of two mandatory subunits including the α-subunit, which mediates ATP hydrolysis and ion translocation, as well as the β-subunit, which acts as a chaperone to promote proper membrane insertion and trafficking in the plasma membrane. To examine the conformational dynamics between the α- and β-subunits of the Na+/K+-ATPase during ion transport, we have used fluorescence resonance energy transfer, under voltage clamp conditions on Xenopus laevis oocytes, to differentiate between two models that have been proposed for the relative orientation of the α- and β-subunits. These experiments were performed by measuring the time constant of irreversible donor fluorophore destruction with fluorescein-5-maleimide as the donor fluorophore and in the presence or absence of tetramethylrhodamine-6-maleimide as the acceptor fluorophore following labeling on the M3-M4 or M5-M6 loop of the α-subunit and the β-subunit. We have also used fluorescence resonance energy transfer to investigate the relative movement between the two subunits as the ion pump shuttles between the two main conformational states (E1 and E2) as described by the Albers-Post scheme. The results from this study have identified a model for the orientation of the β-subunit in relation to the α-subunit and suggest that the α- and β-subunits move toward each other during the E2 to E1 conformational transition.
Y1  - 2021
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/76235
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-762359
SN  - 0021-9258
VL  - 281.2006
IS  - 47
SP  - 36338
EP  - 36346
PB  - American Society for Biochemistry and Molecular Biology Publications
CY  - Bethesda, Md
ER  -