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. 2020 Feb 2;295(14):4464–4476. doi: 10.1074/jbc.RA119.012015

Figure 4.

Figure 4.

Use of iBox-PAK4cat in cellulo crystals as a tool for studying protein-protein interactions. A, schematic of the iBox-PAK4cat PPI assay. Mammalian cells are co-transfected with GFP-PDZ and iBox-PAK4cat constructs containing a C-terminal tetrapeptide motif (iBox-PAK4cat-DTRL and iBox-PAK4cat-AAAA). For iBox-PAK4cat-AAAA no interaction takes place and GFP-PDZ is not incorporated into the iBox-PAK4cat crystal lattice. Conversely, for iBox-PAK4cat-DTRL a PDZ domain-motif interaction occurs and GFP-PDZ is incorporated into the iBox-PAK4cat crystal lattice. The iBox-PAK4cat (red and teal, respectively) in cellulo crystal structure (PDB 4XBR) bound to GFP-PDZ (green and blue, respectively) is modeled for illustrative purposes only. B, fluorescent images of cells co-transfected with GFP-NHERF1 PDZ1 and iBox-PAK4cat-DTRL or iBox-PAK4cat-AAAA, as indicated. Equivalent transmitted light images are shown in Fig. S6. Scale bar bottom right indicates 100 μm.