title: Antibodies to the F1-ATPase of Rhodospirillum rubrum and its purified native beta-subunit: inhibition of ATP-linked activities in R. rubrum and in lettuce.
abstract: 1. Antibodies prepared against the Rhodospirillum rubrum F1-ATPase (RrF1) and its purified, native-beta-subunit, exhibited cross-reactivity with the following soluble preparations of R. rubrum ATPase: RrF0 . F1, RrF1 and the beta-subunit. Anti-RrF1, but not anti-beta antibodies, also formed precipitin lines with soluble beta-less Rrf1, indicating that antigenic determinants of both the beta-subunit and the other four RrF1-subunits are expressed in the whole RrF1 molecule. Both antibodies agglutinated the R. rubrum chromatophores, suggesting that the beta-subunit is located on the external part of RrF1. 2. Both antibodies inhibited ATP synthesis and hydrolysis activities of R. rubrum chromatophores, as well as all the soluble ATPase reactions. Similar concentrations of each antibody were required for 50% inhibition of all these reactions, but anti-RrF1 was always somewhat more effective than anti-beta. These data indicate that the beta-subunit is involved in the catalytic site of the RrF1-enzyme. 3. The antibodies prepared against R. rubrum F1-ATPase and its beta-subunit could bind the soluble chloroplast F1-ATPase (CF1) and inhibited ATP-linked reactions carried out by chloroplasts and by soluble CF1. In these reactions, unlike in the R. rubrum ones, anti-beta was a more potent inhibitor than the anti-RrF1 antibody. The cross-reaction obtained between the antibodies raised against R. rubrum F1 and its beta-subunit and the chloroplast CF1 indicates the presence of similar antigenic determinants in the photosynthetic prokaryotic and eukaryotic F1-ATPases, which have been conserved during evolution.
mesh_terms: D000251:Adenosine Triphosphatases / Q000276:immunology*; D000255:Adenosine Triphosphate / Q000037:antagonists & inhibitors*; D000906:Antibodies / Q000032:analysis; D000937:Antigen-Antibody Reactions; D002462:Cell Membrane / Q000201:enzymology; D002736:Chloroplasts / Q000201:enzymology; D003429:Cross Reactions; D010446:Peptide Fragments / Q000276:immunology; D010766:Phosphorylation; D010944:Plants / Q000201:enzymology*; D006180:Proton-Translocating ATPases; D012247:Rhodospirillum rubrum / Q000201:enzymology*
chemical_list: D000906:Antibodies; D010446:Peptide Fragments; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D006180:Proton-Translocating ATPases