Overexpression of Pex30p and Pex31p restores ER shape in rtn1rtn2yop1Δ cells. (A) Schematic representation of the screen for genes that complement rtn1rtn2yop1spo7Δ cells. (B) The indicated strains were grown to mid-logarithmic growth phase, serially diluted, spotted onto plates that do or do not contain 5-fluoroorotic acid (5-FOA), and incubated at 30°C for 3 d. (C) Fluorescence microscopy images of strains expressing ss-RFP-HDEL focusing on the center (top) or periphery (bottom) of the cells. Arrows indicate normal cortical ER in wild-type (WT) and abnormal cortical ER in mutant. Bars, 3 µm. (D) Quantification of the experiment in C: Percentage of cells with normal ER morphology (mean ± SE; n = 3 biological replicates of at least 200 cells). (E) EM images of indicated strains. Yellow arrows indicate cortical ER; blue arrows, plasma membrane (PM); and green arrows, cell wall (CW). Bottom panel shows ER in yellow. Bars: (wild type) 200 nm; (rtn1rtn2yop1Δ) 100 nm. N, nucleus; V, vacuole.