Initiation codon

a specific mRNA sequence (usually AUG, but sometimes GUG) that is the signal for the addition of fMet-tRNA and for the beginning of translation

Description
The initiation codon codes for the first aminoacid in nascent protein sequences, formylmethionine, which is often removed post-transcriptionally (i.e. co- or post-translationally) Syn start codon