Epitope of OSCP oligomycin sensitivity conferring protein exposed at the surface of the mitochondrial ATPase-ATPsynthase complex.
Immunological studies were designed to study the structure of the oligomycin sensitivity conferring protein (OSCP) integrated in the mitochondrial ATPase-ATPsynthase complex. The monoclonal antibody 2B1B1 used in this study could bind as well to purified or membrane bound OSCP as shown previously by Protein A-gold immunocytochemistry and by competitive immunotitration. In this paper, it is shown that 2B1B1 can also immunoprecipitate the F0F1 complex from a Triton X-100 extract. This means that not only, 2B1B1 binds to the surface of OSCP but also that the binding of 2B1B1 did not destroy the interactions between F0 and F1 and further demonstrates the external location of the 2B1B1 binding site in the ATPase-ATPsynthase complex. This antigenic site was located on the N-terminal sequence of OSCP, between residues 1 and 72, as demonstrated after chemical cleavage of OSCP with formic acid, hydroxylamine and partial cleavage with cyanogen bromide. The proximity of Tyr and Arg to the epitope was suggested by the lack of 2B1B1 binding to iodinated OSCP and by the susceptibility of this binding to trypsin or to endoproteinase Arg-C treatments of OSCP, respectively. A more precise location of the epitope has been attempted by using the method of synthesis of overlapping octapeptides on solid support. It was found that 2 groups of octapeptides could bind 2B1B1. The first group contained in common the sequence Pro7-Pro8-Val9-Gln10-Ile11-Tyr12- and the second group of peptides contained the sequence Arg62-Ser63-Val64-Lys65. Another monoclonal antibody, AF4H7, which competes with 2B1B1, also recognized the first group of peptides. The possible involvement of these 2 fragments in the epitope localized at the surface of OSCP is discussed. In addition, secondary structure theoretical analysis predicts that these 2 domains should be in a beta-strand configuration.
Godinot
C
C
Laboratoire de Biologie et Technologie des Membranes du CNRS, Université Claude Bernard de Lyon I, Villeurbanne, France.
Colorio
S
S
Cretin
F
F
Inçaurgarat
B
B
Deleage
G
G
Roux
B
B
D000251:Adenosine Triphosphatases / Q000032:analysis*; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D000911:Antibodies, Monoclonal; D002352:Carrier Proteins; D002417:Cattle; D000939:Epitopes / Q000032:analysis*; D008565:Membrane Proteins; D008929:Mitochondria, Heart / Q000201:enzymology*; D025261:Mitochondrial Proton-Translocating ATPases; D008954:Models, Biological; D009206:Myocardium / Q000201:enzymology; D009840:Oligomycins; D011233:Precipitin Tests; D011487:Protein Conformation; D006180:Proton-Translocating ATPases; D013552:Swine
D000596:Amino Acids; D000911:Antibodies, Monoclonal; D002352:Carrier Proteins; D000939:Epitopes; D008565:Membrane Proteins; D009840:Oligomycins; D000251:Adenosine Triphosphatases; D025261:Mitochondrial Proton-Translocating ATPases; D006180:Proton-Translocating ATPases; C020439:oligomycin sensitivity-conferring protein