FIG. 1.

RNA2 5′ box B-dependent and 2a ORF-dependent 1a-induced membrane association. (A) Sequences and predicted secondary structure of the RNA2 5′ UTR. The conserved box B motif is boxed, and the three subdomains discussed in Results, which are defined based on alignment with the RNA1 5′ UTR, are indicated. (B) On the left are schematic diagrams of RNA2 and its derivatives. Membrane association abilities of these RNAs in the absence (−1a) or presence (+1a) of 1a were assessed by cell fractionation. Yeast cells expressing these RNAs with or without 1a were spheroplasted and lysed osmotically. The lysate then was centrifuged at 10,000 × g to yield a membrane-containing pellet (P) fraction and a supernatant (S) fraction. RNA was isolated from each fraction by phenol-chloroform extraction, and equal percentages of each fraction were analyzed by Northern blotting to detect positive-strand RNA2. Representative Northern blots are shown at the right.