51.7%GC3 content

56.4Effective codons (Nc)

250Coding sequences

21/26GC3 rank here

Scope: nuclear genes only

NCBI table 1 (Standard). Do not apply these frequencies to mitochondrial genes, where AGA, AGG, ATA and TGA carry different meanings. The four reassignments.

What distinguishes this table

The most constrained choice in Lion is glutamine: of its 2 synonymous codons, CAG takes 69% of the family. Lysine sits at the other end, spread almost evenly across its options (evenness 1.00 against 0.89 for glutamine). Those two families are where a codon-optimizer has the most and the least room to move.

Measured across all 59 sense codons, this table correlates most closely with Tiger (r = 0.992) and least with M. tuberculosis (r = 0.695). A sequence tuned for the first would need little adjustment to move here; one tuned for the second would need a great deal.

Relative to the average across the 26 organisms on this site, Lion leans hardest on TGT (+0.097 against the mean) and avoids TGC most (-0.097). Those two are the codons that most distinguish this table from the others.

Preferred and avoided codons

Amino acid	Preferred	Freq	RSCU	Avoided	Freq	RSCU
Alanine A	GCC	0.383	1.53	GCG	0.139	0.55
Arginine R	AGA	0.238	1.43	CGT	0.093	0.56
Asparagine N	AAT	0.548	1.10	AAC	0.452	0.90
Aspartate D	GAC	0.522	1.04	GAT	0.478	0.96
Cysteine C	TGT	0.557	1.11	TGC	0.443	0.89
Glutamate E	GAG	0.524	1.05	GAA	0.476	0.95
Glutamine Q	CAG	0.694	1.39	CAA	0.306	0.61
Glycine G	GGC	0.321	1.29	GGT	0.175	0.70
Histidine H	CAC	0.524	1.05	CAT	0.476	0.95
Isoleucine I	ATT	0.392	1.18	ATA	0.215	0.65
Leucine L	CTG	0.345	2.07	CTA	0.083	0.50
Lysine K	AAA	0.501	1.00	AAG	0.499	1.00
Phenylalanine F	TTC	0.502	1.00	TTT	0.498	1.00
Proline P	CCT	0.308	1.23	CCG	0.134	0.54
Serine S	TCT	0.212	1.27	TCG	0.069	0.42
Threonine T	ACA	0.315	1.26	ACG	0.136	0.54
Tyrosine Y	TAC	0.530	1.06	TAT	0.470	0.94
Valine V	GTG	0.406	1.62	GTA	0.163	0.65

Full codon usage table

Amino acid	Codon	Frequency	RSCU
Alanine A	GCC	0.3833	1.533
	GCT	0.2405	0.962
	GCA	0.2375	0.950
	GCG	0.1387	0.555
Arginine R	AGA	0.2384	1.430
	AGG	0.2287	1.372
	CGG	0.1839	1.103
	CGC	0.1531	0.919
	CGA	0.1032	0.619
	CGT	0.0926	0.556
Asparagine N	AAT	0.5484	1.097
Asparagine N	AAC	0.4516	0.903
Aspartate D	GAC	0.5217	1.043
Aspartate D	GAT	0.4783	0.957
Cysteine C	TGT	0.5574	1.115
Cysteine C	TGC	0.4426	0.885
Glutamate E	GAG	0.5243	1.049
Glutamate E	GAA	0.4757	0.951
Glutamine Q	CAG	0.6942	1.388
Glutamine Q	CAA	0.3058	0.612
Glycine G	GGC	0.3214	1.286
	GGA	0.2807	1.123
	GGG	0.2231	0.892
	GGT	0.1748	0.699
Histidine H	CAC	0.5244	1.049
Histidine H	CAT	0.4756	0.951
Isoleucine I	ATT	0.3924	1.177
	ATC	0.3923	1.177
	ATA	0.2154	0.646
Leucine L	CTG	0.3452	2.071
	CTC	0.1663	0.998
	TTG	0.1630	0.978
	CTT	0.1364	0.818
	TTA	0.1060	0.636
	CTA	0.0831	0.499
Lysine K	AAA	0.5013	1.003
Lysine K	AAG	0.4987	0.997
Methionine M	ATG	1.0000	1.000
Phenylalanine F	TTC	0.5019	1.004
Phenylalanine F	TTT	0.4981	0.996
Proline P	CCT	0.3078	1.231
	CCC	0.2946	1.178
	CCA	0.2632	1.053
	CCG	0.1344	0.538
Serine S	TCT	0.2120	1.272
	AGC	0.1985	1.191
	TCC	0.1923	1.154
	TCA	0.1671	1.003
	AGT	0.1607	0.964
	TCG	0.0693	0.416
Threonine T	ACA	0.3149	1.260
	ACC	0.2795	1.118
	ACT	0.2701	1.080
	ACG	0.1355	0.542
Tryptophan W	TGG	1.0000	1.000
Tyrosine Y	TAC	0.5303	1.061
Tyrosine Y	TAT	0.4697	0.939
Valine V	GTG	0.4057	1.623
	GTT	0.2320	0.928
	GTC	0.1992	0.797
	GTA	0.1632	0.653

Provenance

Computed from 250 RefSeq coding sequences for Panthera leo, sampled and counted codon by codon. Frequencies are relative within each amino acid family. Page generated 2026-08-09.

The full derivation of GC3, RSCU and the effective number of codons, along with the limits of each, is set out once in the methods note rather than repeated on every page.

Use this table

Nucleora codon-optimizes a coding sequence against this table directly, then folds the result and reports where structure would interfere with expression.

Request access All 26 organisms