Ascidian mitochondrial code
Mitochondrial genetic code in tunicates
From Wikipedia, the free encyclopedia
The ascidian mitochondrial code (translation table 13) is a genetic code found in the mitochondria of Ascidia.
Code
AAs = FFLLSSSSYY**CCWWLLLLPPPPHHQQRRRRIIMMTTTTNNKKSSGGVVVVAAAADDEEGGGGStarts = ---M------------------------------MM---------------M------------Base1 = TTTTTTTTTTTTTTTTCCCCCCCCCCCCCCCCAAAAAAAAAAAAAAAAGGGGGGGGGGGGGGGGBase2 = TTTTCCCCAAAAGGGGTTTTCCCCAAAAGGGGTTTTCCCCAAAAGGGGTTTTCCCCAAAAGGGGBase3 = 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)
Differences from the standard code
| DNA codons | RNA codons | This code (13) | Standard code (1) | |
|---|---|---|---|---|
AGA | AGA | Gly (G) | Arg (R) | |
AGG | AGG | Gly (G) | Arg (R) | |
ATA | AUA | Met (M) | Ile (I) | |
TGA | UGA | Trp (W) | STOP = Ter (*) |
Systematic range and comments
There is evidence from a phylogenetically diverse sample of tunicates (Urochordata) that AGA and AGG code for glycine. In other organisms, AGA/AGG code for either arginine or serine and in vertebrate mitochondria they code a STOP. Evidence for glycine translation of AGA/AGG was first found in 1993 in Pyura stolonifera[1] and Halocynthia roretzi.[2] It was then confirmed by tRNA sequencing[3] and sequencing whole mitochondrial genomes.[4][5]
Alternative initiation codons
- ATA, GTG and TTG[5]
- ATT is the start codon for the CytB gene in Halocynthia roretzi.[6]
