The vertebrate mitochondrial code (translation table 2) is the

genetic code The genetic code is the set of rules used by living cells to translate information encoded within genetic material ( DNA or RNA sequences of nucleotide triplets, or codons) into proteins. Translation is accomplished by the ribosome, which links ...

found in the

mitochondria A mitochondrion (; ) is an organelle found in the cells of most Eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is u ...

of all

vertebrata Vertebrates () comprise all animal taxa within the subphylum Vertebrata () (chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with c ...

Evolution

AGA and AGG were thought to have become mitochondrial

stop codon In molecular biology (specifically protein biosynthesis), a stop codon (or termination codon) is a codon ( nucleotide triplet within messenger RNA) that signals the termination of the translation process of the current protein. Most codons i ...

s early in vertebrate evolution. However, at least in humans it has now been shown that AGA and AGG sequences are not recognized as termination codons. A -1

mitoribosome The mitochondrial ribosome, or mitoribosome, is a protein complex that is active in mitochondria and functions as a riboprotein for translating mitochondrial mRNAs encoded in mtDNA. The mitoribosome is attached to the inner mitochondrial membran ...

frameshift occurs at the AGA and AGG codons predicted to terminate the CO1 and ND6

open reading frame In molecular biology, open reading frames (ORFs) are defined as spans of DNA sequence between the start and stop codons. Usually, this is considered within a studied region of a prokaryotic DNA sequence, where only one of the six possible readin ...

s (ORFs), and consequently both ORFs terminate in the standard UAG codon.

Incomplete stop codons

Mitochondrial genes in some vertebrates (including humans) have incomplete

s ending in U or UA, which become complete termination codons (UAA) upon subsequent

polyadenylation Polyadenylation is the addition of a poly(A) tail to an RNA transcript, typically a messenger RNA (mRNA). The poly(A) tail consists of multiple adenosine monophosphates; in other words, it is a stretch of RNA that has only adenine bases. In euka ...

Translation table

: The codon AUG both codes for methionine and serves as an initiation site: the first AUG in an

mRNA In molecular biology, messenger ribonucleic acid (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a gene, and is read by a ribosome in the process of synthesizing a protein. mRNA is created during t ...

's coding region is where translation into protein begins.

Differences from the standard code

Alternative initiation codons

* ''

Bos ''Bos'' (from Latin '' bōs'': cow, ox, bull) is the genus of wild and domestic cattle. ''Bos'' is often divided into four subgenera: ''Bos'', ''Bibos'', ''Novibos'', and ''Poephagus'', but including these last three divisions within the ge ...

'': AUA * ''

Homo ''Homo'' () is the genus that emerged in the (otherwise extinct) genus ''Australopithecus'' that encompasses the extant species ''Homo sapiens'' (modern humans), plus several extinct species classified as either ancestral to or closely related ...

'': AUA, AUU * '' Mus'': AUA, AUU, AUC * ''

Coturnix ''Coturnix'' is a genus of five extant species and five to eight known extinct species of Old World quail. These species are distributed throughout Africa, Eurasia, Australia, and formerly New Zealand. An extinct radiation of flightless, insul ...

'', '' Gallus'': also GUG

References

* This article contains public domain text from the

NCBI The National Center for Biotechnology Information (NCBI) is part of the United States National Library of Medicine (NLM), a branch of the National Institutes of Health (NIH). It is approved and funded by the government of the United States. T ...