Amino acid composition in endothermic vertebrates is biased in the same direction as in thermophilic prokaryotes

Table 2 Typical temperature ranges for the 11 vertebrate species, and compositional bias of 339 co-orthologs.

Class	Species	T (°C)	ERK	%AT-rich	%GC-rich
Mammalia	Mus musculus	36.9	-16.32	23.22	24.56
Mammalia	Rattus norvegicus	37.3	-16.27	22.82	24.91
Mammalia	Human	37	-16.11	23.82	24.31
Mammalia	Bos taurus	38	-15.97	23.14	25.00
Birds	Gallus gallus	39	-16.01	23.59	24.83
Reptilia	Anolis carolinensis	26 (24- 28)	-17.03	23.75	24.45
Amphibia	Xenopus laevis	21(18-22)	-16.53	25.29	22.52
Amphibia	Xenopus tropicalis	25 (23-28)	-16.53	25.22	22.72
Fish	Danio rerio	28.5	-16.76	23.85	23.45
Fish	Tetraodon nigroviridis	27(25-28)	-16.53	25.22	22.72
Fish	Takifugu rubripes	25(23-26)	-17.17	23.31	23.8
p		0.0080	0.0075	0.25	0.13

p-values (bottom row) are for comparison of endothermic (mammalia, birds) to ectothermic (reptilia, amphibia, fish) vertebrates, treating each genomic average as a single data point (Wilcoxon rank sum tests). The two last columns list the proportion of AT-rich amino acids (F, Y, M, I, N, K) and GC-rich amino acids (G, A, R, P).

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