start codon

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in·i·ti·a·ting co·don

the trinucleotide AUG (or sometimes GUG) that codes for the first amino acid in protein sequences, formylmethionine; the latter is often removed post-transcriptionally.
Synonym(s): start codon

start codon

A codon, AUG in eukaryotes and either GUG or UUG in bacteria, that signals the initiation of translation and the first amino acid in a polypeptide chain. Also called chain initiation codon.

start codon


a triplet in a chain of nucleic acids in mRNA that specifies the order in which amino acids are added. The codon triplet pairs with a sequence of three complementary nucleotides, called the anticodon, present in the anticodon arm of tRNA. Called also triplet. See also deoxyribonucleic acid.

start codon
see initiation codon.
stop c's
three codons, UAG, UAA and UGA, also referred to as amber, ochre and opal codons, in mRNA which terminate translation.
termination codon
see stop codons (above).