New insights into prion biology from the novel [SWI⁺] system

Figures & data

Figure 1 Amino acid sequences of prion domains of known prions. Asparagine (N) residues are highlighted in blue, glutamine (Q) residues are highlighted in purple, and serine (S), tyrosine (Y) and threonine (T) are highlighted in red. Underlined areas indicate the imperfect oligopeptide repeats in Sup35 and Rnq1.

Table 1 Percentage of amino acids present in prion domains of known yeast prions

	Swi1 (1–524)	Sup35 (1–123)	Ure2 (1–89)	Rnq1 (153–405)	Average protein
Ala	6	5	1	5	5
Cys	0.2	0	0	0	1
Asp	3	2	2	0	6
Glu	2	0	3	1	6
Phe	4	2	2	4	4
Gly	3	17	6	17	5
His	1	0	1	2	2
Ile	4	0	3	0	6
Lys	3	1	1	0	7
Leu	6	1	3	3	10
Met	2	1	2	2	2
Asn	23	16	37	16	6
Pro	4	5	0	1	4
Gln	14	29	11	27	4
Arg	3	2	5	1	4
Ser	11	4	11	15	8
Thr	8	0	6	1	6
Val	3	0	5	0	5
Trp	0.2	0	0	0	1
Tyr	2	16	0	6	3

Blue bars denote glutamine and asparagine, and orange bars indicate amino acids that appear to be overrepresented in prion domains. All percentages are rounded to the nearest whole number, with the exception of Cys and Trp for Swi1. The average amino acid composition of all yeast ORFs is shown for comparison (data from ref. 2, Fig. 1A).

Table 2 Swi1 is unique among yeast prions proteins due to its nuclear localization and low cellular abundance

	Localization	# of molecules/cell
Sup35	cytoplasmic	78900
Ure2	cytoplasmic	7060
Rnq1	cytoplasmic	1140
Swi1	nuclear	250

Data on number of molecules per cell from www.yeastgenome.org.

Echols N, Harrison P, Balasubramanian S, Luscombe NM, Bertone P, Zhang Z, et al. Comprehensive analysis of amino acid and nucleotide composition in eukaryotic genomes, comparing genes and pseudogenes. Nucleic Acids Res 2002; 30:2515 - 2523

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