Developmentally regulated Atg40 expression drives selective ERphagy in meiosis. (A) Western blot with samples taken from WT, atg39Δ, atg40Δ, and atg39Δatg40Δ cells expressing Rtn1-GFP at the indicated times after transfer to SPO, probed for GFP and hexokinase. (B) Average and SD quantifying free GFP as a proportion of total GFP signal for n = 3 replicates of the experiment in A. P values calculated by Student’s t test. *, P < 0.05; **, P < 0.01; ****, P < 0.0001. (C) Microscopy of cells of the indicated genotypes expressing Rtn1-GFP and Vph1-mCherry and imaged at the indicated times after transfer to SPO. Scale bar = 2 µm. (D) Western blot with samples taken from cells expressing Rtn1-GFP and Atg40-3V5 at the indicated times after transfer to SPO, probed for GFP, V5, and hexokinase. (E) Time-lapse microscopy of cells expressing Atg40-3xGFP and mKate-Spo20^51–91 (PSM) imaged every 10 min in meiosis. Note increased Atg40-3xGFP signal intensity in collapsed ER relative to earlier and later time points. Scale bar = 2 µm. (F) Western blot with samples taken from ime1Δ cells expressing Rtn1-GFP and Atg40-3V5 under the endogenous promoter (pATG40-ATG40-3V5) or the CUP1 promoter (pCUP1-ATG40-3V5). For YPD samples, cells were diluted to 0.05 OD units in YPD, allowed to grow to exponential phase, and treated with 50 µM CuSO₄. For SPO samples, cells were transferred to SPO for 2 h and treated with 50 µM CuSO₄. Protein samples were taken at the indicated times after CuSO₄ treatment. (G) Average and SD quantifying percentage tetrad formation for cells of the indicated genotypes measured 24 h following transfer to SPO. n = 4 replicates were performed, with ≥100 cells counted per replicate. P values calculated by Student’s t test as in B. ns, P > 0.05. Source data are available for this figure: SourceData F6.