N-Formylmethionine (FMET)

f-Formylmethionine (fMet) is a proteinogenic amino acid found in Bacteria and related Eukaryotic organelles. It is a derivative of the amino acid methionine in which a formyl group has been added to the amino group. It is specifically used for initiation of protein synthesis, and may be removed after.fMet plays a crucial part in the protein synthesis of bacteria, mitochondria and chloroplasts. It is not used in cytosolic protein synthesis of eukaryotes, where eukaryotic nuclear genes are translated. It is also not used by Archaea. fMet is a starting residue in the synthesis of proteins in prokaryotes and, consequently, is located at the N-terminus of the growing polypeptide. fMet is delivered to the ribosome (30S) - mRNA complex by a specialized tRNA (tRNA.fMet) which has a 5'-CAU-3' anticodon that is capable of binding with the AUG start codon located on the mRNA.