Three-dimensional structure of the porcine gastric H,K-ATPase from negatively stained crystals.
A low-resolution three-dimensional model of membrane-bound H,K-ATPase from pig gastric mucosa has been reconstructed by electron microscopy and image processing of two-dimensional crystals in negative stain. The crystal formation is induced by magnesium and vanadate, which stabilize the E2 conformation of the enzyme. The unit cell, with a size of a = b = 123 A, gamma = 90 degrees, has tetragonal p4 symmetry. There are four separate alpha beta protomers within each unit cell. The high-contrast region is limited to the cytoplasmic part of the protein. The total volume of the observed asymmetric protein domain corresponds to a molecular mass of 80-90 kDa. It consists mainly of a large pear-shaped domain measuring 60 x 45 A2, with a height of 50 A as measured perpendicular to the membrane plane. A small stalk segment, 20 A in length, forms a connection to the transmembrane region.
Xian
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Y
Department of Biosciences at Novum, Karolinska Institutet, Huddinge, Sweden.
Hebert
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H
D000818:Animals; D003460:Crystallization; D005753:Gastric Mucosa / Q000201:enzymology*; D017506:H(+)-K(+)-Exchanging ATPase / Q000737:chemistry* / Q000648:ultrastructure*; D007091:Image Processing, Computer-Assisted; D008854:Microscopy, Electron; D008958:Models, Molecular; D015394:Molecular Structure; D008970:Molecular Weight; D011487:Protein Conformation; D013552:Swine
D017506:H(+)-K(+)-Exchanging ATPase