Identity of the N-terminal sequences of the three A chains of mistletoe (V.ALBUM L.) lectins: homology with ricin-like plant toxins and single-chain ribosome-inhibiting proteins

Journal/Book: Anti-Cancer Drugs 3, 507-511. 1992;

Abstract: Mistletoe lectin (ML) I increases the production of cytokines bymononuclear cells and has been proposed as a useful biological responsemodifier in the treatment of cancer. Two other lectins, ML II and MLIII, have been identified in mistletoe. We report that the N-terminalsequences of the three A chains of ML I, ML II and ML III are identical,and have interesting homology with the N-terminal sequences of the Achain of ricin-like toxins and of single-chain ribosome-inhibitingproteins. In addition, the three mistletoe lectins inhibit the growth ofthe human tumor cell line Molt 4, ML III being the most potent, followedby ML II and ML I. This inhibition is suppressed by addition of rabbitanti-ML I antibodies to the cultured cells. The data obtained suggestthat the three lectins have amino acid sequences which show extensivehomology and exert very similar biological effects. They may be derivedfrom the same precursor.

Keyword(s): Medical:tumor-cell

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