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- Title
Inter-subunit interaction of gastric H<sup>+</sup>,K<sup>+</sup>-ATPase prevents reverse reaction of the transport cycle.
- Authors
Abe, Kazuhiro; Tani, Kazutoshi; Nishizawa, Tomohiro; Fujiyoshi, Yoshinori
- Abstract
The gastric H+,K+-ATPase is an ATP-driven proton pump responsible for generating a million-fold proton gradient across the gastric membrane. We present the structure of gastric H+,K+-ATPase at 6.5 Å resolution as determined by electron crystallography of two-dimensional crystals. The structure shows the catalytic α-subunit and the non-catalytic β-subunit in a pseudo-E2P conformation. Different from Na+,K+-ATPase, the N-terminal tail of the β-subunit is in direct contact with the phosphorylation domain of the α-subunit. This interaction may hold the phosphorylation domain in place, thus stabilizing the enzyme conformation and preventing the reverse reaction of the transport cycle. Indeed, truncation of the β-subunit N-terminus allowed the reverse reaction to occur. These results suggest that the β-subunit N-terminus prevents the reverse reaction from E2P to E1P, which is likely to be relevant for the generation of a large H+ gradient in vivo situation.
- Publication
EMBO Journal, 2009, Vol 28, Issue 11, p1637
- ISSN
0261-4189
- Publication type
Academic Journal
- DOI
10.1038/emboj.2009.102