Invertebrate mitochondrial code

The invertebrate mitochondrial code is a genetic code used by the mitochondrial genome of invertebrates.

The code

   AAs = FFLLSSSSYY**CCWWLLLLPPPPHHQQRRRRIIMMTTTTNNKKSSSSVVVVAAAADDEEGGGG

Starts = ---M----------------------------MMMM---------------M------------

 Base1 = TTTTTTTTTTTTTTTTCCCCCCCCCCCCCCCCAAAAAAAAAAAAAAAAGGGGGGGGGGGGGGGG

 Base2 = TTTTCCCCAAAAGGGGTTTTCCCCAAAAGGGGTTTTCCCCAAAAGGGGTTTTCCCCAAAAGGGG

 Base3 = TCAGTCAGTCAGTCAGTCAGTCAGTCAGTCAGTCAGTCAGTCAGTCAGTCAGTCAGTCAGTCAG

Bases: adenine (A), cytosine (C), guanine (G) and thymine (T) or uracil (U).

Amino acids: Alanine (Ala, A), Arginine (Arg, R), Asparagine (Asn, N), Aspartic acid (Asp, D), Cysteine (Cys, C), Glutamic acid (Glu, E), Glutamine (Gln, Q), Glycine (Gly, G), Histidine (His, H), Isoleucine (Ile, I), Leucine (Leu, L), Lysine (Lys, K), Methionine (Met, M), Phenylalanine (Phe, F), Proline (Pro, P), Serine (Ser, S), Threonine (Thr, T), Tryptophan (Trp, W), Tyrosine (Tyr, Y), Valine (Val, V)

Note: The codon AGG is absent in Drosophila.

Differences from the standard code:

	This code	Standard
AGA	Ser S	Arg R	AGG	Ser S	Arg R	AUA	Met M	Ile I	UGA	Trp W	Ter *

Alternative initiation codons:

• AUA, AUU
• AUC: Apis
• GUG: Polyplacophora
• UUG: Ascaris, Caenorhabditis

Systematic range

• Nematoda: Ascaris, Caenorhabditis;
• Mollusca: Bivalvia (Hoffmann et al., 1992); Polyplacophora (Boore and Brown, 1994)
• Arthropoda/Crustacea: Artemia (Batuecas et al., 1988)
• Arthropoda/Insecta: Drosophila [Locusta migratoria (migratory locust), Apis mellifera (honeybee)]

Other variations

• Several arthropods translate the codon AGG as lysine instead of serine (as in the Pterobranchia Mitochondrial Code) or arginine (as in the standard genetic code) (Abascal et al., 2006).
• GUG may possibly function as an initiator in Drosophila (Clary and Wolstenholme, 1985; Gadaleta et al., 1988). AUU is not used as an initiator in Mytilus (Hoffmann et al., 1992).
• "An exceptional mechanism must operate for initiation of translation of the cytochrome oxidase subunit I mRNA in both D. melanogaster (de Bruijn, 1983) and D. yakuba (Clary and Wolstenholme 1983), since its only plausible initiation codon, AUA, is out of frame with the rest of the gene. Initiation appears to require the "reading" of of an AUAA quadruplet, which would be equivalent to initiation at AUA followed immediately by a specific ribosomal frameshift. Another possible mechanism ... is that the mRNA is "edited" to bring the AUA initiation into frame." (Fox, 1987)

References

• This article contains public domain text from the NCBI page compiled by Andrzej (Anjay) Elzanowski, Jim Ostell, Detlef Leipe, Vladimir Soussov..