Table 1.

Comparison of Substrate Properties among the Modules

	Variable	As Isa	Random	Correlation with Expression Level in the Networkb
Expression	Expression level	2.22 × 10−16**	0.62	—
	CAI	2.38 × 10−06**	0.37	0.54**
	Optimal codons	1.18 × 10−05**	0.76	0.53**
Secondary structure	Alpha helix	0.0067**	0.08	0.02
	Coiled coils	0.0256**	0.4	0.21**
	Beta sheets	0.0833	0.53	0.21**
Physiochemical properties	Protein length	4.13 × 10−09**	0.94	−0.17**
	Hydrophobic amino acids	0.2177	0.23	0.18**
	Negative amino acids	0.0008**	0.56	0.08**
	Positive amino acids	0.5682	0.72	−0.06**
	Polar amino acids	0.0081**	0.83	−0.31**
	Aromaticity index	0.0017**	0.43	−0.04**
	Gravy	0.171	0.58	0.14**
Amino acid frequencies	Alanine	6.60 × 10−07**	0.89	0.36**
	Arginine	0.3581	0.8	−0.09**
	Asparagine	0.0384*	0.58	−0.27**
	Aspartate	4.71 × 10−05**	0.08	0.03
	Cysteine	0.5354	0.23	−0.09**
	Glutamine	0.0064**	0.87	−0.08**
	Glutamate	0.2669	0.97	0.09**
	Glycine	0.0172**	0.24	0.25**
	Histidine	0.4528	0.07	−0.10**
	Isoleucine	0.0027**	0.11	−0.06**
	Leucine	0.0031**	0.47	−0.08**
	Lysine	0.4807	0.75	0.03**
	Methionine	0.3369	0.61	−0.08**
	Phenyl-alanine	0.0012**	0.48	−0.04**
	Proline	0.0074**	0.43	−0.07**
	Serine	0.0417*	0.07	−0.29**
	Threonine	0.4651	0.72	−0.05**
	Tryptophan	0.0612	0.48	0.03
	Tyrosine	0.0586	0.31	0.02
	Valine	0.0185**	0.27	0.27**
Evolutionary rate	Substitution rate	2.15 × 10−06**	0.36	−0.42**
	% Identical amino acids	1.35 × 10−07**	0.81	0.47**
	Substitutions per site	2.58 × 10−07**	0.75	−0.46**

^aUsing Kruskal–Wallis test for equality of median ranks with the null hypothesis, H₀: μ_module1 = μ_module2 = … = μ_module10.

^bUsing Spearman rank correlation coefficient.

^*P value < 0.05.

^**P value < 0.05 using false discovery rate test for multiple comparisons.