Binding sites for A2 and A24 monoclonal antibodies on the alpha-latrotoxin molecule

alpha-Latrotoxin (alpha-LTX) binding sites to functionally active monoclonal antibodies (MA) A4 and A24 were localized using three approaches: hydrolysis of the toxin followed by the N-terminal sequencing of immunoreactive peptides; the study of antibody interaction with several recombinant alpha-LTX fragments; and Western immunoblotting of synthetic overlapping peptides (6-8 aa) whose structures correspond to that of the immunoreactive alpha-LTX fragment. It was shown that the MA A4 epitope is located within the F234-M294 protein fragment and that of MA A24 interacts with the fragment 347FDKDIT352.