Method of expressing proteins comprising non-naturally-occurring amino acids

Abstract

A method of expressing a protein having an unnatural amino acid integrated thereinto comprising expressing (A) a mutant tyrosyl tRNA synthase that is derived from-origin tyrosyl tRNA synthase and has an elevated specificity for an unnatural tyrosine derivative compared with the specificity for tyrosine, (B) a suppressor tRNA originating in an eubacterium belonging to the genusorwhich is capable of binding to the above tyrosine derivative in the presence of the above mutant TyrRS, and (C) a desired protein gene having a nonsense mutation at a desired site in animal cells to thereby incorporate the above tyrosine derivative into the nonsense mutation site in the above protein.