Journal: Nature Cell Biology
Article Title: Ca 2+ -driven PDIA6 biomolecular condensation ensures proinsulin folding
doi: 10.1038/s41556-025-01794-8
Figure Lengend Snippet: a , Mean diameter of ensemble particles in solution ( Z -average) of PDIA1, PDIA3, PDIA4, PDIA6, PDIA10 and PDIA15 under various Ca 2+ concentrations. The values are the mean ± s.d. of three independent experiments. b , Liquid droplets observed by DIC microscopy when 50 μM PDIA6 and 4 mM CaCl 2 were mixed at pH 7.2. This experiment was replicated three times independently. c , PDIA6 phase diagram obtained by DIC microscopy when 5–100 μM PDIA6 and 0.5–10 mM CaCl 2 were mixed at pH 7.2. Dominant PDIA6 states at varying protein and Ca²⁺ concentrations are indicated by symbols: black circles, dispersed state; black triangles, condensed state. The dashed black line represents the critical droplet concentration. Three independent experiments were performed. d , Confocal fluorescence images of PDIA6 droplets before and after photobleaching. The white arrowhead indicates the laser irradiation area. Rapid recovery of mCherry–PDIA6 fluorescence after photobleaching (left). Increases in the normalized fluorescence intensity of mCherry–PDIA6 after photobleaching (five replicates; right). The fluorescence recovery t 1/2 was calculated from the normalized fluorescence intensity of the five replicates. e , Liquid droplets observed by DIC microscopy when 50 μM PDIA6 and 4 mM CaCl 2 were mixed with (right) or without (left) NaCl. This experiment was replicated three times independently. f , Liquid droplets observed by DIC microscopy when 50 μM PDIA6 and 4 mM CaCl 2 were mixed in solutions with different pH values. This experiment was replicated three times independently. g , Time course of representative two-dimensional (2D) RI distribution (top), and bright-field (middle) and fluorescence images (bottom) of FUS and PDIA6 droplets monitored by 3D holographic imaging (green, ThT fluorescence; three independent experiments). [Ca 2+ ], Ca 2+ concentration; BF, bright field; FI, fluorescence image; [PDIA6], PDIA6 concentration.
Article Snippet: Primary antibodies to PDIA6 (1:1,000; Proteintech, 18233-1-AP), CNX (1:1,000; MBL, M178-3), mCherry (1:1,000; Proteintech, 26765-1-AP; 1:1,000; Proteintech, 68088-1-Ig), BiP (1:1,000; Abcam, ab21685) and PDIA3 (1:1,000; Proteintech, 15967-1-AP) were used.
Techniques: Microscopy, Concentration Assay, Fluorescence, Irradiation, Imaging