Translational repression is a prerequisite for mRNA targeting to Ire1 foci
a,d,f–g, Localization of Ire1-mCherry, and U1A-GFP decorated mRNA of either the wild-type splicing reporter, as in Figure 2i (SpR WT), or an intron-less variant (SpR Δintron) (a), or of PGK1U1A, bearing either the wild-type (d,f) or mutant Δ3′BE (g) 3′UTR stem loop of HAC1 mRNA, in combination with (f,g) or without (d) a small stem loop (SL) that confers translational repression in its 5′UTR, as schematically depicted. b, C.I for mRNA recruitment of WT and Δintron SpR variants into Ire1 foci (means +/− s.e.m., n = 5); bar for the Δ3′BE mutant as depicted in Figure 2i is shown for comparison. c, Northern blot of HAC1 mRNA from yeast strains that over-expressed variants of the SpR, as indicated. e, Western blot of the variants of HA-tagged Pgk1 protein (HA-Pgk1p) bearing the 3′UTR from HAC1 with or without a 5′UTR SL a,c–g, ER stress was induced with 10 mM DTT for 45 min. h, C.I. for mRNA recruitment into Ire1 foci of PGK1U1A wild-type — see Figure 2f — or variants shown in d,f,g (means +/− s.e.m., n = 3–5).