Characterization of monoclonal antibodies against mitochondrial F1-ATPase.

Four stable murine hybridoma clones producing homogeneous antibodies against pig heart mitochondrial F1-ATPase have been established. All antibodies exhibit specific binding to F1-ATPase. Three of them interact with the beta subunit and one binds strongly to the alpha and barely to the beta subunit. All of them exhibit linear Scatchard plots and high binding affinities, with dissociation constants between 4.7 X 10(-8) M and 6.5 X 10(-10) M. The minimal number of moles of IgG bound at saturation per mole of immobilized F1-ATPase is 2.2 for the anti-alpha-subunit antibody and 2.5 for one anti-beta-subunit antibody. This suggests that more than two copies of the alpha and beta subunits are present in the enzyme. Two antibodies seem to recognize F1-ATPase equally before or after denaturation with sodium dodecyl sulfate. The two other antibodies exhibited a much higher affinity for the nondissociated enzyme, indicating that they are very sensitive to a specific conformation of the enzyme.