Fig. 3: Tetraspanin 8 is localized at the plasma membrane of mucin-secreting cells.

a Optical plane of a representative confocal image of mucin-secreting cells transfected with Tspan-8·RFP and immunolabelled for the Na⁺/K⁺-ATPase α1. Right image shows the merge of the two. Scale bar is 5 µm. b Quantification of the Pearson Correlation Coefficient (PCC) between Tspan-8·RFP and Na⁺/K⁺-ATPase α1. As control, Na⁺/K⁺-ATPase α1 images were rotated 90° right and the PCC was calculated. Each dot represents the PCC of one image with at least three cells. n = 9. The red dot is the mean value of the gray dots +/− the standard deviation. One-way ANOVA test p < 0.001. c Optical plane from a confocal image of live mucin-secreting cells expressing Tspan-8·GFP at endogenous levels. To visualize the plasma membrane, cells were incubated with the lipophilic membrane marker CellBrite®. Right image shows the merge of the two. Arrows point to the plasma membrane. Scale bar is 5 µm. Five images from two independent cell cultures showed similar results. d WT HT29-N2 cell lines were processed to obtain plasma membrane-enriched fractions. Purified samples were analyzed by western blot. As controls, top and middle panels show immunoblotting against Na⁺/K⁺-ATPase α1 and beta tubulin respectively. One of three independent experiment is shown. All replicates showed similar results. Source data for b and d are provided as a Source Data file.