Fig. 4: Protein expression and colocalization of DPP4 mutants.

a Differential expression of wtDPP4 and its mutants (250 KDa) as analyzed by western blotting, tubulin stained as loading control (55 KDa). b Dual staining of wtDPP4, ΔK6DPP4, ΔcytDPP4, ACE2 or pcDNA (red) and MERS-CoV spike S1 protein (green) to visualize colocalization (yellow), white squares indicate zoomed area, scale bar = 10 µm. c Transmembrane length prediction of wtDPP4 and ΔK6 using the TMHMM v2.0 tool. d Schematic representation of the predicted arrangement of ΔK6DPP4 on the cell membrane in comparison with wtDPP4. e Alphafold3 predicted models of wtDPP4 and ΔK6DPP4 superimposed on each other showing a bend and increase in length of ΔK6DPP4 transmembrane domain as compared to wtDPP4.