Genetic Codes

While there is much commonality, different parts of the tree of life use slightly different genetic codes. When translating from genome to protein, the use of the correct genetic code is essential. The mitochondrial codes are the relatively well-known examples of variation. The translation table list below follows the numbering and designation by NCBI. Four novel alternative genetic codes were discovered in bacterial genomes by Shulgina and Eddy using their codon assignment software Codetta, and validated by analysis of tRNA anticodons and identity elements; these codes are not currently adopted at NCBI, but are numbered here 34-37, and specified in the table below.

# The standard code
# The vertebrate mitochondrial code
# The yeast mitochondrial code
# The mold, protozoan, and coelenterate mitochondrial code and the mycoplasma/spiroplasma code
# The invertebrate mitochondrial code
# The ciliate, dasycladacean and hexamita nuclear code
# The deleted kinetoplast code; ''cf''. table 4.
# deleted, ''cf''. table 1.
# The echinoderm and flatworm mitochondrial code
# The euplotid nuclear code
# The bacterial, archaeal and plant plastid code
# The alternative yeast nuclear code
# The ascidian mitochondrial code
# The alternative flatworm mitochondrial code
# The ''Blepharisma'' nuclear code
# The chlorophycean mitochondrial code
# (none)
# (none)
# (none)
# (none)
# The trematode mitochondrial code
# The ''Scenedesmus obliquus'' mitochondrial code
# The ''Thraustochytrium'' mitochondrial code
# The Pterobranchia mitochondrial code
# The candidate division SR1 and gracilibacteria code
# The ''Pachysolen tannophilus'' nuclear code
# The karyorelict nuclear code
# The ''Condylostoma'' nuclear code
# The ''Mesodinium'' nuclear code
# The peritrich nuclear code
# The ''Blastocrithidia'' nuclear code
# The Balanophoraceae plastid code (not shown on web)
# The Cephalodiscidae mitochondrial code
# The Enterosoma code
# The Peptacetobacter code
# The Anaerococcus and Onthovivens code
# The Absconditabacterales genetic code

The alternative translation tables (2 to 37) involve codon reassignments that are recapitulated in the DNA and RNA codon tables.

Table summary

Comparison of alternative translation tables for all codons (using IUPAC amino acid codes):

Notes

Three translation tables have a peculiar status:
* Table 7 is now merged into translation table 4.
* Table 8 is merged to table 1; all plant chloroplast differences due to RNA edit.
* Table 32 is not shown on the web page, but is present in the ASN.1 format "gc.prt" release.

The list of genetic codes provided by NCBI does not take into account the "special" two proteinogenic amino acids:
* Selenocysteine (Sec or U), which requires a rather complicated translation machinery to insert involving a special elongation factor and the mRNA SECIS element. See .
* Pyrrolysine (Pyl or O), which requires no special machinery to insert so long as Pyl-tRNA^Pyl is available. As a result, it can and has appeared in proteins through neutral missense mutations.

Other mechanisms also play a part in protein biosynthesis, such as post-transcriptional modification.

References

See also

* Genetic codes: list of alternative codons

External links

NCBI List of Alternative Codes

Further reading

*
* {{Cite journal, url=http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0074-02762007000600016, journal=Mem. Inst. Oswaldo Cruz, volume=102 , issue=6, location= Rio de Janeiro , date=31 July 2007, title=Effects of ''Trypanosoma brucei'' tryptophanyl-tRNA synthetases silencing by RNA interference , author1=Liliana Torcoroma García , author2=Ney Ribeiro Leite , author3=Juan D Alfonzo , author4=Otavio Henrique Thiemann

Codes
Gene expression