Table 1.

Prion propensity, order propensity and prevalence for each amino acid

Amino acid	Prion propensitya	Prevalence in prion domainsb	Hydrophobicityc
Phenylalanine	0.84	2.5	0.81
Isoleucine	0.81	1.1	1.0
Valine	0.81	1.5	0.97
Tyrosine	0.78	7.8	0.36
Methionine	0.67	1.7	0.71
Tryptophan	0.67	0	0.40
Cysteine	0.42	0	0.78
Serine	0.13	10.0	0.41
Asparagine	0.080	23.5	0.11
Glutamine	0.069	22.0	0.11
Glycine	−0.039	12.9	0.46
Leucine	−0.040	2.3	0.92
Threonine	−0.12	2.1	0.42
Histidine	−0.28	0.9	0.14
Alanine	−0.40	3.9	0.70
Arganine	−0.41	2.5	0.00
Glutamic Acid	−0.61	1.5	0.11
Proline	−1.20	1.7	0.32
Aspartic Acid	−1.28	1.3	0.11
Lysine	−1.58	0.7	0.07

^aExperimentally determined prion propensity from ref. 1. Prion propensities were calculated as the natural log of the fold over/under-representation of the amino acid among prion-forming clones relative to the naïve library.

^bThe average percent prevalence among the Sup35, rnq1 and Ure2 prion domains.

^cFrom ref. 21, rescaled from 0 to 1. This scale is used by FoldIndex to calculate intrinsic folding propensity (I_F) by the equation I_F = 2.785<H> — <R> — 1.151, where <H> is the mean hydrophobicity and <R> is average net charge.²⁰