Editing Stop codon (section)

{{short description|Codon that marks the end of a protein-coding sequence}}
[[File:Homo sapiens-mtDNA~NC 012920-ATP8+ATP6 Overlap.svg|thumb|right|400px|Stop codon (red dot) of the human mitochondrial DNA ''MT-ATP8'' gene, and start codon (blue circle) of the ''MT-ATP6'' gene. For each nucleotide triplet (square brackets), the corresponding amino acid is given (one-letter code), either in the +1 [[reading frame]] for ''MT-ATP8'' (in red) or in the +3 frame for ''MT-ATP6'' (in blue). In this genomic region, the two genes [[Overlapping gene|overlap]].]]

In [[molecular biology]], a '''stop codon''' (or '''termination codon''') is a [[Genetic code|codon]] ([[nucleotide]] triplet within [[messenger RNA]]) that signals the termination of the [[translation (biology)|translation]] process of the current [[protein]].<ref>{{cite book|vauthors=((Griffiths AJF)), Miller JH, Suzuki DT, Lewontin RC, Gelbart WM | title=An Introduction to Genetic Analysis| year=2000| publisher=W.H. Freeman |chapter=10. Molecular Biology of Gene Function: Genetic code: §Stop codons |isbn=978-0-7167-3520-5 |oclc=42049331 |edition=7th}}</ref> Most codons in messenger RNA correspond to the addition of an [[amino acid]] to a growing [[polypeptide]] chain, which may ultimately become a protein; stop codons signal the termination of this process by binding [[release factor]]s, which cause the [[Ribosome|ribosomal]] subunits to disassociate, releasing the amino acid chain.

While [[start codon]]s need nearby sequences or [[initiation factor]]s to start translation, a stop codon alone is sufficient to initiate termination.