59.1%GC3 content

52.9Effective codons (Nc)

248Coding sequences

10/26GC3 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 Cat is glutamine: of its 2 synonymous codons, CAG takes 73% of the family. Cysteine sits at the other end, spread almost evenly across its options (evenness 0.99 against 0.84 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 Dog (r = 0.998) and least with Ferret (r = 0.823). 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, Cat leans hardest on GCC (+0.060 against the mean) and avoids CAT most (-0.054). 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	0.449	1.80	GCG	0.112	0.45
Arginine R	AGA	0.234	1.40	CGT	0.066	0.40
Asparagine N	AAC	0.573	1.15	AAT	0.427	0.85
Aspartate D	GAC	0.570	1.14	GAT	0.430	0.86
Cysteine C	TGC	0.548	1.10	TGT	0.452	0.90
Glutamate E	GAG	0.569	1.14	GAA	0.431	0.86
Glutamine Q	CAG	0.732	1.46	CAA	0.268	0.54
Glycine G	GGC	0.355	1.42	GGT	0.152	0.61
Histidine H	CAC	0.618	1.24	CAT	0.383	0.77
Isoleucine I	ATC	0.499	1.50	ATA	0.167	0.50
Leucine L	CTG	0.416	2.50	CTA	0.059	0.35
Lysine K	AAG	0.567	1.13	AAA	0.433	0.87
Phenylalanine F	TTC	0.569	1.14	TTT	0.431	0.86
Proline P	CCC	0.357	1.43	CCG	0.122	0.49
Serine S	AGC	0.250	1.50	TCG	0.062	0.38
Threonine T	ACC	0.377	1.51	ACG	0.140	0.56
Tyrosine Y	TAC	0.588	1.18	TAT	0.412	0.82
Valine V	GTG	0.469	1.88	GTA	0.098	0.39

Full codon usage table

Amino acid	Codon	Frequency	RSCU
Alanine A	GCC	0.4491	1.796
	GCT	0.2422	0.969
	GCA	0.1965	0.786
	GCG	0.1122	0.449
Arginine R	AGA	0.2338	1.403
	AGG	0.2193	1.316
	CGG	0.1966	1.180
	CGC	0.1834	1.100
	CGA	0.1007	0.604
	CGT	0.0662	0.397
Asparagine N	AAC	0.5732	1.146
Asparagine N	AAT	0.4268	0.854
Aspartate D	GAC	0.5699	1.140
Aspartate D	GAT	0.4301	0.860
Cysteine C	TGC	0.5479	1.096
Cysteine C	TGT	0.4521	0.904
Glutamate E	GAG	0.5687	1.137
Glutamate E	GAA	0.4313	0.863
Glutamine Q	CAG	0.7322	1.464
Glutamine Q	CAA	0.2678	0.536
Glycine G	GGC	0.3551	1.420
	GGA	0.2532	1.013
	GGG	0.2401	0.960
	GGT	0.1516	0.606
Histidine H	CAC	0.6175	1.235
Histidine H	CAT	0.3825	0.765
Isoleucine I	ATC	0.4993	1.498
	ATT	0.3336	1.001
	ATA	0.1671	0.501
Leucine L	CTG	0.4162	2.497
	CTC	0.2159	1.295
	TTG	0.1332	0.799
	CTT	0.1122	0.673
	TTA	0.0633	0.380
	CTA	0.0591	0.355
Lysine K	AAG	0.5672	1.134
Lysine K	AAA	0.4328	0.866
Methionine M	ATG	1.0000	1.000
Phenylalanine F	TTC	0.5691	1.138
Phenylalanine F	TTT	0.4309	0.862
Proline P	CCC	0.3573	1.429
	CCT	0.2717	1.087
	CCA	0.2491	0.996
	CCG	0.1219	0.488
Serine S	AGC	0.2504	1.502
	TCC	0.2338	1.403
	TCT	0.1864	1.118
	AGT	0.1397	0.838
	TCA	0.1272	0.763
	TCG	0.0625	0.375
Threonine T	ACC	0.3765	1.506
	ACA	0.2553	1.021
	ACT	0.2279	0.912
	ACG	0.1403	0.561
Tryptophan W	TGG	1.0000	1.000
Tyrosine Y	TAC	0.5876	1.175
Tyrosine Y	TAT	0.4124	0.825
Valine V	GTG	0.4694	1.878
	GTC	0.2668	1.067
	GTT	0.1656	0.662
	GTA	0.0982	0.393

Provenance

Computed from 248 RefSeq coding sequences for Felis catus, 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.

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