Tyrosine-130 in bullfrog thyroglobulin is a thyroid hormone generating site

Bullfrog thyroglobulin was digested with lysyl endopeptidase, known to be highly specific to cut the C-terminal side of lysine residue in protein, after reduction and carboxymethylation. We isolated one peptide which lacked the C-terminal lysine, and which corresponds to 103-129 of bovine thyroglobulin sequence. Tyrosine 130 in the mammalian thyroglobulin molecule is known to be an iodination site. These findings suggest that tyrosine 130 in frog thyroglobulin is a thyroid hormone generating site.