|Title||Structure of the rotor of the V-Type Na+-ATPase from Enterococcus hirae.|
|Publication Type||Journal Article|
|Year of Publication||2005|
|Authors||Murata, T, Yamato, I, Kakinuma, Y, Leslie, AGW, Walker, JE|
|Date Published||2005 Apr 29|
|Keywords||Adenosine Triphosphatases, Adenosine Triphosphate, Amino Acid Sequence, Bacterial Proteins, Binding Sites, Crystallography, X-Ray, Detergents, Enterococcus, Ion Transport, Models, Biological, Models, Molecular, Molecular Motor Proteins, Molecular Sequence Data, Phospholipids, Protein Conformation, Protein Structure, Tertiary, Protein Subunits, Sodium, Static Electricity, Water|
The membrane rotor ring from the vacuolar-type (V-type) sodium ion-pumping adenosine triphosphatase (Na+-ATPase) from Enterococcus hirae consists of 10 NtpK subunits, which are homologs of the 16-kilodalton and 8-kilodalton proteolipids found in other V-ATPases and in F1Fo- or F-ATPases, respectively. Each NtpK subunit has four transmembrane alpha helices, with a sodium ion bound between helices 2 and 4 at a site buried deeply in the membrane that includes the essential residue glutamate-139. This site is probably connected to the membrane surface by two half-channels in subunit NtpI, against which the ring rotates. Symmetry mismatch between the rotor and catalytic domains appears to be an intrinsic feature of both V- and F-ATPases.