Angiotensin II receptor subtypes in the duck subfornical organ: an electrophysiological and receptor autoradiographic investigation

Cross-talk in the A1-ATPase from Methanosarcina mazei Gö1 Due to Nucleotide Binding

“…The formation of A-B oligomers reflects the proximity of these subunits, which are proposed to alternate around a cavity in a hexameric fashion, thereby locating the nucleotide-binding sites at their interfaces (2,40). Significantly, A-A dimers can be observed even though separated by an intervening B subunit.…”

“…The enzyme was isolated by gel permeation chromatography followed by ion exchange chromatography, as will be described elsewhere. 1 For solution x-ray scattering experiments (see below) the enzyme was subsequently applied onto a Sephacryl S-300 HR column (10/30, Amersham Biosciences) equilibrated in 50 mM Tris-HCl (pH 6.9), 150 mM NaCl and subjected to gel permeation chromatography (FPLC) 2 in order to isolate a homogeneous and nucleotide-depleted A 1 complex (14). The purity and homogeneity of the protein sample was analyzed by Native-PAGE (18) and SDS-PAGE (19).…”

“…In particular, the F 1 -ATPase has a significantly shorter stalk than A 1 , ϳ40 -45 Å long and 50 -53 Å wide (12,15). The prevailing view is, however, that ATP hydrolysis in the A 1 headpiece is coupled to ion flow in A O through movements of the central stalk subunit(s) (2) as visualized by optical microscopy for F 1 by fixing this enzyme on a surface and attaching either an actin filament or a bead to the ␥ subunit to mark its orientation (reviewed in Ref. 16).…”

“…The membrane-integrated archaeal A 1 A O -ATPase (A 3 B 3 CDEFGHIK x , the exact stoichiometry of the subunits is unknown), like the bacterial F 1 F O -ATPase (␣ 3 ␤ 3 ␥␦⑀abc x ) and the eucaryotic V 1 V O -ATPase (A 3 B 3 CDEFG x H y ac z de), possesses an extrinsic domain (A 1 ), containing the catalytic sites, and an intrinsic domain (A O ), involved in ion translocation (1)(2)(3). The primary structure of the archaeal ATPase is very similar to that of the V-ATPase, but its function, as an ATP-synthase, is more similar to that of F-ATPases (2, 4 -6).…”

Purification and characterization of a membrane-associated ATPase from Natronococcus occultus, a haloalkaliphilic archaeon

“…It has been shown that cold inactivation of ATPases results in the dissociation of the peripheral part of the enzyme [22]. This dissociation can occur even at room temperature [23]. The addition of 30% sorbitol or 20% glycerol (common halophile enzyme stabilizers) was not e¡ective in maintaining activity (data not shown).…”