Table 2.

Prion domain of Ure2p is sufficient for [URE3] propagation

Strain 1 URE2		Strain 2 ure2Δ		Strain 3 URE2
1 3560 USA+/[URE3]	→	pURE2 (38 of 43 USA+)	→	D350-3CC (16 all USA+)
2 3560 USA+/[URE3]	→	pURE2C (22 all USA−)	→	3748 (20 all USA−)
3 3560 USA+/[URE3]	→	pURE2N (29 all USA+)	→	3748 (42 of 57 USA+)
4 3560 USA+/[URE3]	→	pURE2N + pURE2C (24 all USA−)	→	D350-3CC (15 of 16 USA+)

Cytoplasm is transferred from [URE3] cells (strain 1) to a ure2Δ strain (strain 2) producing all or part of Ure2p from a plasmid. Strain 2 is USA⁺ with no plasmid. pURE2 is pDM16 expressing the entire Ure2p, pURE2N is pDM14 expressing residues 1-65 of Ure2p (the prion-inducing domain, and pURE2C is pDM12 expressing residues 66–354, the nitrogen regulation domain (9). The strain 2 cytoductants are tested for their phenotypes and used as cytoduction donors to strain 3, which is URE2. The USA phenotype of strain 3 reveals whether [URE3] is propagating in strain 2. → indicates transfer of cytoplasm by cytoduction. Strain 1 (3560) = MATa ura2 kar1-1 hisx leu2 p530 (YEpURE2) [URE3]. Strain 2 (4444-3A) = MATα ura2 ure2Δ his3 leu2 ρ⁰ with various plasmids. Strain 3 (3748) = MATa ura2 kar1-1 ade2 ρ^o [ure-o] or (D350-3CC) = MATa ura2 kar1-1 leu2 trp1 can1 ρ^o [ure-o].