Аннотация:Extracts from mistletoe (Viscum album L.) contain three main toxic proteins -the lectins MLI (also known as vls-cumln), MLII and MLIII. A catalytic subu-nlt of the mistletoe plant toxic lectin MLIII has been cloned and expressed In Escherichia coli cells. The structure and immunochemical properties of recombinant MLIII A-subunlt were Investigated using a panel of monoclonal antibodies against ML-toxlns. Rlbosome-lnactlvating activity of the recombinant MLIII A-subunlt was determined In a cell-free system exhibiting Inhibition of endogenous protein synthesis. The comparative analysis of nucleotide and deduced amino acid sequences of the cloned MLIII A and the native MLI A-subunlts was performed, revealing the main differences In the primary structure of these proteins. Antigenicity analysis of the MLIII A-subunlt has revealed a new epitope d179-E184 that is not present in viscumln. The role of toxic lectins with respect to the immunological properties of mistletoe extracts Is discussed.