Fig. 6: PGRMC1 selects small cargos for degradation.

a–d HEK 293 T cells expressing A16P-Myc were transfected with scrambled, PGRMC1, RTN3 or Beclin1 siRNA. The soluble and insoluble fractions were collected, layered over a discontinuous 10–50% sucrose gradient, and centrifuged. Each fraction was collected, subjected to SDS-PAGE, and immunoblotted as indicated. Quantification of three separate replicates for each sucrose gradient is shown below each panel. Data are represented as mean ± SD. e HEK 293 T cells expressing A16P-Myc and FLAG-PGRMC1 were transfected with Beclin1 siRNA. FLAG IP was performed as in Fig. 2f, and the bound material was eluted using 3xFLAG peptide. Whole-cell lysate (input) and the precipitated material were subject to sucrose gradient analysis followed by SDS-PAGE and immunoblotting as described in a–d. N = 3 independent experiments. f HEK 293 T parental or PGRMC1 KO cells expressing B8V-Myc or B8V(A6/A11)-Myc were lysed, subject to SDS-PAGE, and immunoblotted as indicated. N = 3 independent experiments. g Quantification of mutant proinsulin from f (top panels) relative to parental cells. Data are represented as mean ± SD. N = 3 independent experiments. One-tailed Standard Student’s t-test was used to determine statistical significance. h As in a–d except cells were co-transfected with PGRMC1 and Beclin1 siRNAs. N = 3 independent experiments. *P ≤ 0.05; **P ≤ 0.005. Source data are provided as a Source Data file. See also Fig. S5.