title: [Cloning and expression of the cholera toxin B subunit gene].
abstract: The CT-B gene-expressing plasmid pXB1 and modified pXB2 were constructed using recombinant DNA techniques. These resulted in high CT-B gene expression in E. coli (280-350 ng/ml), with CT-B accounting for 71.5% of total extracellular protein. The results of CT-B expression kinetics showed that the CT-B product levels reached a peak after 24 h in culture. Certain concentrations (100 micrograms/ml) of MgCl2, L-histidine and asparagine can increase the CT-B product level by 10%-25%. The binding of the expressed CT-B product to GM1 receptor on free or live cell membranes was identified by GM1-ELISA, CHO cytotoxicity test, indirect immunofluorescence, and the rabbit ileal loop test. No toxic response to cells or rabbits was detected.
authors.affiliation: Institute of Epidemiology and Microbiology, Chinese Academy of Preventive Medicine, Beijing.
authors.forename: J
authors.initials: J
authors.lastname: Tian
mesh_terms: D000818:Animals; D016466:CHO Cells; D002772:Cholera Toxin / Q000235:genetics* / Q000494:pharmacology; D003001:Cloning, Molecular; D006224:Cricetinae; D004274:DNA, Recombinant; D004926:Escherichia coli / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D010446:Peptide Fragments / Q000235:genetics* / Q000494:pharmacology; D010957:Plasmids; D011817:Rabbits
chemical_list: D004274:DNA, Recombinant; D010446:Peptide Fragments; C050310:cholera toxin, B subunit (50-64); D002772:Cholera Toxin