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IMGT Aide-mémoire

Genetic code

Nucleotide position in codon
first second third
U C A G
U UUU Phe
UUC Phe
UUA Leu
UUG Leu 		UCU Ser
UCC Ser
UCA Ser
UCG Ser 		UAU Tyr
UAC Tyr
UAA Stop
UAG Stop 		UGU Cys
UGC Cys
UGA Stop
UGG Trp 		U
C
A
G
C CUU Leu
CUC Leu
CUA Leu
CUG Leu 		CCU Pro
CCC Pro
CCA Pro
CCG Pro 		CAU His
CAC His
CAA Gln
CAG Gln 		CGU Arg
CGC Arg
CGA Arg
CGG Arg 		U
C
A
G
A AUU Ile
AUC Ile
AUA Ile
AUG Met 		ACU Thr
ACC Thr
ACA Thr
ACG Thr 		AAU Asn
AAC Asn
AAA Lys
AAG Lys 		AGU Ser
AGC Ser
AGA Arg
AGG Arg 		U
C
A
G
G GUU Val
GUC Val
GUA Val
GUG Val 		GCU Ala
GCC Ala
GCA Ala
GCG Ala 		GAU Asp
GAC Asp
GAA Glu
GAG Glu 		GGU Gly
GGC Gly
GGA Gly
GGG Gly 		U
C
A
G
Amino acids and codons
Amino acids Codons
A Ala Alanine GCA GCC GCG GCU
C Cys Cysteine UGC UGU
D Asp Aspartic acid GAC GAU
E Glu Glutamic acid GAA GAG
F Phe Phenylalanine UUC UUU
G Gly Glycine GGA GGC GGG GGU
H His Histidine CAC CAU
I Ile Isoleucine AUA AUC AUU
K Lys Lysine AAA AAG
L Leu Leucine UUA UUG CUA CUC CUG CUU
M Met Methionine AUG
N Asn Asparagine AAC AAU
P Pro Proline CCA CCC CCG CCU
Q Gln Glutamine CAA CAG
R Arg Arginine AGA AGG CGA CGC CGG CGU
S Ser Serine AGC AGU UCA UCC UCG UCU
T Thr Threonine ACA ACC ACG ACU
V Val Valine GUA GUC GUG GUU
W Trp Tryptophan UGG
Y Tyr Tyrosine UAC UAU
Stop codons UAA UGA UAG
Stop codons
In the standard genetic code, there are three different stop codons
RNA RNA DNA References
amber UAG TAG [1]
ochre UAA TAA [2]
opal UGA TGA [3]
Bacteria 'amber codon suppressor' strains carry a mutation in the tRNA that recognizes the amber stop codon, allowing translation to read through the codon and to produce a full-length protein, thereby "suppressing" the amber mutation.
Escherichia coli strain ER2537, TG1 and XL1-Blue are amber codon (UAG) suppressor strains, while HB2151 is an amber codon non-suppressor strain.
Infection of the E. coli HB2151 non-suppressor strain by scFv-phages or Fab-phages is used for the obtention of soluble scFv or soluble Fab in the supernatant.

The Genetic Code

The universal genetic code includes 20 common amino acids. In addition, selenocysteine (Sec) and pyrrolysine (Pyl), known as the twenty first and twenty second amino acids, are encoded by UGA and UAG, respectively, which are the codons that usually function as stop signals. Search for a putative twenty-third amino acid in archeal and bacterial genomes has been negative so far [4].

Restriction enzyme sites

Useful restriction sites
BamHI G↓GATCC
EcoRI G↓AATTC
HindIII A↓AGCTT
KpnI GGTAC↓C
PstI CTGCA↓G
PvuII CAG↓CTG
SacI (SstI) GAGCT↓C
TaqI T↓CGA
XbaI T↓CTAGA
XhoI C↓TCGAG

REBASE, The Restriction Enzyme Database, restriction enzymes and methylases.

References:
[1] Stahl FW (1995). The amber mutants of phage T4. Genetics, 141(2):439-442. PMCID: PMC1206745 Freely accessible. PMID: 8647382.
[2] Brenner S, Stretton AOW, Kaplan S (1965). Genetic Code: The 'Nonsense' Triplets for Chain Termination and their Suppression. Nature, 206(4988):994-998. PMID: 5320272. doi:10.1038/206994a0.
[3] Brenner S, Barnett L, Katz ER, Crick FHC (1967). UGA: A Third Nonsense Triplet in the Genetic Code. Nature, 213(5075):449-450. PMID: 6032223.
[4] Lobanov AV et al. (2006). Is there a twenty third amino acid in the genetic code? Trends in Genetics, 22(7):357-360. PMID: 16713651. doi:10.1016/j.tig.2006.05.002.