title: Structure of the rotor of the V-Type Na+-ATPase from Enterococcus hirae.
abstract: 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.
authors.affiliation: Medical Research Council Dunn Human Nutrition Unit, Hills Road, Cambridge CB2 2XY, UK.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Murata
authors.forename: Ichiro
authors.initials: I
authors.lastname: Yamato
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Kakinuma
authors.forename: Andrew G W
authors.initials: AG
authors.lastname: Leslie
authors.forename: John E
authors.initials: JE
authors.lastname: Walker
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D018360:Crystallography, X-Ray; D003902:Detergents / Q000378:metabolism; D016983:Enterococcus / Q000201:enzymology*; D017136:Ion Transport; D008954:Models, Biological; D008958:Models, Molecular; D020409:Molecular Motor Proteins / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D055672:Static Electricity; D014867:Water
chemical_list: D001426:Bacterial Proteins; D003902:Detergents; D020409:Molecular Motor Proteins; D010743:Phospholipids; D021122:Protein Subunits; D014867:Water; D000255:Adenosine Triphosphate; D012964:Sodium; D000251:Adenosine Triphosphatases; C500332:V-type sodium ATPase, Enterococcus hirae