Patent ID: 7723069

Claim:
A method for site specific incorporation of phosphoserine into a protein or polypeptide comprising a) providing a nucleic acid sequence encoding a gene with tRNASep activity b) providing a nucleic acid sequence encoding a gene with SepRS activity c) expressing the nucleic acids of step a) and step b) wherein the SepRS preferentially aminoacylates tRNASep with phosphoserine and the tRNASep recognizes at least one codon such that phosphoserine is incorporated into a protein or polypeptide, wherein the nucleic acid sequences encoding genes with tRNASep and SepRS activities are from the genome of Archaeoglobus fulgidus , or of a methanogenic archaea selected from the group consisting of M. jannaschii, M. maripaludis, M. thermautotrophicus, M. kandleri , or the Methanosarcinacae.