FIG. 4.

Prion domain(s) of Ure2p. Deletion mutants overexpressing fragments of Ure2p from a plasmid were assayed for the ability to induce the de novo formation of [URE3] in a strain expressing the full-length Ure2p from the chromosomal gene, and, separately, for the ability to complement the nitrogen regulation defect of a ure2Δ mutation. (A) The region from positions 1 to 65 is sufficient for prion induction. (B) A fragment of Ure2p lacking the region from positions 1 to 65 can also induce [URE3]. (C) Regions that promote prion formation (black) and block prion formation (white) are shown. Modified from reference 65 with permission of the publisher.