Comparative studies on kinetics of inhibition of protein synthesis in intact cells by ricin and a conjugate of ricin B-chain with momordin

Shalini Sharma, Sunil K. Podder, Anjali A. Karande

Research output: Contribution to journalArticle

16 Scopus citations


Ribosome inactivating proteins from plants have been widely used for the preparation of immunotoxins and hormonotoxins, which have potential application in the therapy of diseases such as cancer. However, these hybrid toxins have been found to be less cytotoxic than native ribosome inactivating proteins. Therefore, it is important to understand the factors that control the intrinsic toxicity of RIPs and the hybrid toxins prepared using them. Here, a hybrid toxin has been prepared by coupling ricin B-chain to momordin and the cytotoxicity of this hybrid toxin has been compared to that observed in case of native ricin. In the two cell types used here, thymocytes and macrophages, the conjugate was found to be about 40 fold less toxic than native ricin. Kinetics of inhibition of protein synthesis showed that prior to onset of inhibition the conjugate exhibits a longer lag phase than native ricin. The rates of inhibition of protein synthesis by the conjugate were also found to be slower than ricin. Analysis of the results suggests that in addition to cell surface binding, the B-chain of ricin facilitates another step in the transmembrane translocation of ricin A-chain to the cytosol.

Original languageEnglish (US)
Pages (from-to)133-141
Number of pages9
JournalMolecular and Cellular Biochemistry
Issue number1-2
StatePublished - Oct 29 1999
Externally publishedYes



  • Momordin
  • Ribosome inactivating proteins (RIPs)
  • Ricin
  • Ricin A-chain

ASJC Scopus subject areas

  • Molecular Biology
  • Clinical Biochemistry
  • Cell Biology

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