ジャーナル: EMBO J / 年: 2009 タイトル: Inter-subunit interaction of gastric H+,K+-ATPase prevents reverse reaction of the transport cycle. 著者: Kazuhiro Abe / Kazutoshi Tani / Tomohiro Nishizawa / Yoshinori Fujiyoshi / 要旨: 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 ...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 A resolution as determined by electron crystallography of two-dimensional crystals. The structure shows the catalytic alpha-subunit and the non-catalytic beta-subunit in a pseudo-E(2)P conformation. Different from Na(+),K(+)-ATPase, the N-terminal tail of the beta-subunit is in direct contact with the phosphorylation domain of the alpha-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 beta-subunit N-terminus allowed the reverse reaction to occur. These results suggest that the beta-subunit N-terminus prevents the reverse reaction from E(2)P to E(1)P, which is likely to be relevant for the generation of a large H(+) gradient in vivo situation.
濃度: 2.5 mg/ml / 包埋: NO / シャドウイング: NO / 染色: NO / 凍結: YES
急速凍結
装置: REICHERT-JUNG PLUNGER / 凍結剤: NITROGEN / 凍結前の試料温度: 277 K
結晶化
手法: microdialysis / pH: 4.87 詳細: 20 mM propionate, 1 mM MgCl2, 0.5 mM AlCl3, 4 mM NaF, 0.3 mM ADP, 3 mM DTT, 10% (w/v) glycerol, pH 4.87, MICRODIALYSIS