A method to assess compositional bias in biological sequences and its application to prion-like glutamine/asparagine-rich domains in eukaryotic proteomes

Table 4 Numbers of (Q+N)-rich domains for the six proteomes

Category		Budding yeast	Fission yeast	Fruit fly	Nematode	Arabidopsis	Human
1	(Q+N)-rich domains according to a Q, N or Q+N bias*	172	22	853	315	213	194
2	(1) plus filter for charged and hydrophobic residues^†	96	14	473	216	125	69
3	(2) plus requirement for a subsidiary bias for G, Y or S^‡	31	7	86	80	35	21

*The total number of (Q+N)-rich domains. These are all LPSs that have a Q or N bias with P_bias < 1 × ^10-13 or a {QN} bias with P_bias < 1.8 × ^10-14. †A filter is used so that only LPSs that have a subsidiary bias against {DERK} with a P_bias < 6.5 × ^10-3 and against {VILM} with a P_bias < 2 × ^10-2 are considered. ^‡A filter is used so that only LPSs that have a subsidiary bias for one of the residues G, Y or S with a P_bias < 5 × ^10-4 are considered.