Nonsynonymous variants in EFL1 disrupt 80S assembly with varying severity. (A) Polysome profiling results of EFL1^+/+ and EFL1^−/− cells followed by transfection of vectors containing EFL1^WT, EFL1^p.Thr1069Ala, or EFL1^p.His30Arg (as indicated in the top right corner of each plot). Note the different heights of 60S and 80S peaks in each experiment (dotted lines). (B) Immunoblot showing the CRISPR knockout of EFL1 in HeLa cells. (C) Quantification of the polysome profiling results displaying the relative occupancy of different ribosome statuses. Each bar corresponds to each experiment in panel B. (D) Immunoblots of EFL1 and eIF6 in wild-type or EFL1^−/− HeLa cells with or without transfection of vectors containing EFL1^WT, EFL1^p.Thr1069Ala, or EFL1^p.His30Arg. (E) Immunoblots of eIF6 from ribosomal fractions that best represent 60S and 80S of HeLa cells; each corresponds to the polysome profiles shown above. GAPDH, glyceraldehyde-3-phosphate dehydrogenase.