Cloning and expression of recombinant, functional ricin B chain.

M. S. Chang, D. W. Russell, J. W. Uhr, E. S. Vitetta

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25 Scopus citations


The cDNA encoding the B chain of the plant toxin ricin has been cloned and expressed in monkey kidney COS-M6 cells. The recombinant B chain was detected by labeling the transfected cells with [35S]methionine and [35S]-cysteine and demonstrating the secretion of a protein with a Mr of 30,000-32,000 that was not present in the medium of mock-transfected COS-M6 cells. This protein was specifically immunoprecipitated by an anti-ricin or anti-B-chain antibody and the amount of recombinant B chain secreted by the COS-M6 cells was determined by a radioimmunoassay. Virtually all of the recombinant B chain formed active ricin when mixed with native A chain; it could also bind to the galactose-containing glycoprotein asialofetuin as effectively as native B chain. These results indicate that the vast majority of recombinant B chains secreted into the medium of the COS-M6 cells retain biological function.

Original languageEnglish (US)
Pages (from-to)5640-5644
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number16
StatePublished - Aug 1987

ASJC Scopus subject areas

  • General


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