Nucleotide sequences of the genes for Escherichia coli heat-stable enterotoxin I of bovine, avian, and porcine origins

: The nucleotide sequences of cloned Escherichia coli heat-stable toxin 1 (STI) genes isolated from bovine, avian, and porcine origins were determined. They were found to be almost identical to that of Tn1681. The nucleotide sequences were completely preserved in bovine and avian genes, whereas the porcine gene had different sequences at 3 positions in the external region of STI structural genes, as compared with Tn1681. The amino acid sequences of the STI genes of the 3 animal origins corresponded to STIa, which had initially been found in a bovine strain.