Primary structure of cholera toxin beta-chain: a glycoprotein hormone analog?

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Science  21 Jan 1977:
Vol. 195, Issue 4275, pp. 299-301
DOI: 10.1126/science.831277


The completed sequence of the beta-chain of cholera toxin (103 amino acid residues) was compared to the beta-chains of chorionic gonadotropin, thyrotropin, luteinizing, and follicle stimulating hormones. The overall chemical similarity of the toxin beta-chain to the hormones was not statistically different from random; however, a comparison of the first 40 residues of the toxin beta-chain to the glycoprotein hormones revealed a segment of the hormones which was significantly chemically similar. The probability was less than .003 that the similarity was due to chance.