Journal: bioRxiv
Article Title: ER-associated protein degradation initiates by retrotranslocation from the ER quality control compartment
doi: 10.64898/2026.02.04.703732
Figure Lengend Snippet: a, b. H2a-BAP – BirA expressing HEK 293 cells, left untreated (a) or treated with Bz (2.5 µM, 3 hours) (b), were homogenized and post-nuclear supernatants were layered on iodixanol step gradients (10, 16, 22, 28 and 34%) and centrifuged at 24,000 r.p.m. for 16 hours. 1 mL fractions were collected from the top and analyzed by Western blot with StAv-HRP to detect biotinylated H2a-BAP and with α-SV5 (or α-Myc) for total H2a-BAP, together with organelle markers α-CNX, α-HRD1, α-Sec61β, α-20S, α-RPL26 and α-Cab45; the deglycosylated H2a-BAP species is indicated by a red arrow. c . H2a-Myc lacking the BAP tag was co-expressed with BirA as a negative control for biotinylation. d. For each protein, the signal in every fraction was expressed as a percentage of total and plotted versus fraction number; one representative experiment of three is shown. Yellow shading marks fractions enriched in membrane-bound organelles, with fractions 1–2 containing soluble proteins and low-density organelles (Golgi), and green shading marks the ERQC peak. e. HEK 293 cells expressing H2a-BAP - BirA were treated with the p97 inhibitor CB5083 (2.5 µM, 3 hours), alone or with Bz (2.5µM, 3 hours), and analyzed by Western blot. f. Glycosylated and deglycosylated biotinylated H2a-BAP species (from (e)) were quantified, normalized to total H2a-BAP (α-SV5) and expressed relative to untreated cells (mean of 5 experiments ± SD; ordinary two-way ANOVA with Tukey’s multiple-comparisons test).
Article Snippet: Streptavidin-HRP (Jackson ImmunoResearch-016-030-084; 1:5000-7500; WB), Rabbit-α-SV5 (CellSignalling-D3H8Q; 1:2000 (WB), 1:750 (IF), 1:250 (ExM)), Mouse-α-SV5 (GeneScript-A01724-100; 1:1000 (WB), 1:750 (IF), 1:250 (ExM)), Rabbit-α-SYVN (Hrd1) (CellSignaling-14773; 1:1000 (WB), 1:100 (IF)), Rabbit-α-H2a (against N-terminus of H2a as described in ) Rabbit-α-Calnexin (Abcam-92573; 1:5000 (WB)), Rabbit-α-RPL26 (CellSignaling-5400; 1:1000 (WB)), Mouse-α-eIF2α (MBL-AT6031; 1:1000 (WB)), Rabbit-α-C9 (20S) (Abcam-ab118902; 1:1000 (WB)), Rabbit-α-Calnexin (SigmaAldrich - C4731; 1:1000 (WB), 1:500 (IF)), Rabbit-α-Calreticulin (CellSignaling-D3E6; 1:400 (IF)).
Techniques: Expressing, Western Blot, Negative Control, Membrane