Fig. 3: Pore of the ligase complex.
From: A peroxisomal ubiquitin ligase complex forms a retrotranslocation channel
a, Space-filling model of the membrane-embedded part of the ligase complex, viewed from the cytosol. The RF tower was omitted for clarity. The putative plug is shown in purple. b, Magnified view of the central pore, with residues lining the pore highlighted and viewed from the lumen. The dimensions of the pore are indicated. A short segment of a luminal loop, shown as a dashed line, is invisible in the density map. c, As in b, but with the predicted pore size reduced by the indicated mutations. The corresponding mutations in S. cerevisiae are given in brackets. d, Wild-type (WT) or mutant Pex2 or Pex12 were expressed as FLAG-tagged proteins from the endogenous promoter in S. cerevisiae cells lacking Pex2 and Pex12 (pex2Δ pex12Δ) (for expression levels, see Extended Data Fig. 5h). Peroxisomal protein import was determined by the reduction in the formation of a fluorescent pigment (PDV). Fluorescence was measured in cell lysates and the data were normalized, setting the fluorescence of pex2Δ pex12Δ cells as 100% and that of WT cells as 0%. The bar graphs show individual data points, the mean and the s.e.m. from the three biological repeats. Statistical significance between WT and mutants was calculated by one-way analysis of variance. ***P < 0.01 and ****P < 0.0001. See also Source Data file. e, Side view of a cut through a space-filling model of the membrane-embedded regions, with the plug shown as density with the embedded cartoon model. The ring finger domains are shown in full. The white dashed lines indicate two different routes for polypeptides from the lumen to the cytosol. The left path can only be taken when the plug is displaced. The yellow dashed line indicates the plane where pore-reducing residues are located (c,d).
