PMID: 29618813

Authors:

Abe K, Irie K, Nakanishi H, Suzuki H, Fujiyoshi Y

Title:

Crystal structures of the gastric proton pump.

Journal:

Nature. 2018 Apr;556(7700):214-218. doi: 10.1038/s41586-018-0003-8. Epub 2018 Apr, 4.

Abstract:

The gastric proton pump-the H(+), K(+)-ATPase-is a P-type ATPase responsible for acidifying the gastric juice down to pH 1. This corresponds to a million-fold proton gradient across the membrane of the parietal cell, the steepest known cation gradient of any mammalian tissue. The H(+), K(+)-ATPase is an important target for drugs that treat gastric acid-related diseases. Here we present crystal structures of the H(+), K(+)-ATPase in complex with two blockers, vonoprazan and SCH28080, in the luminal-open state, at 2.8 A resolution. The drugs have partially overlapping but clearly distinct binding modes in the middle of a conduit running from the gastric lumen to the cation-binding site. The crystal structures suggest that the tight configuration at the cation-binding site lowers the pK a value of Glu820 sufficiently to enable the release of a proton even into the pH 1 environment of the stomach.