CDNA encoding the type I iodothyronine 5'deiodinase

摘要

The present invention is directed to the cloning, sequencing, and uses of a nucleotide sequence encoding the mammalian enzyme Type I iodothyronine 5' deiodinase and mutant sequences thereof. This enzyme catalyzes the conversion of thyroxine to triiodothyronine, producing the active form of thyroid hormone. The invention is further directed to the discovery that an untranslated nucleotide sequence is necessary for the recognition of a TGA (termination) codon in the coding region of 5' deiodinase as encoding selenocysteine, an amino acid essential for the full activity of 5' deiodinase. The mechanism by which this recognition occurs involves a stem-loop structure in the 3' untranslated region of the mRNA. The untranslated sequence can be used to incorporate selenocysteine into non-selenocysteine-containing proteins and polypeptides.