Fig. 3: Pocket prediction, perturbation and structural analysis of identified MEK1 functional regions.

Predicted pockets at the helical tunnel site (a) and the PPI site (b) are shown as coloured spheres. MEK1 surfaces (non-transparent and transparent surface) and cartoons are colour-coded by sgRNA bins in a heatmap style. Colour codes of the sgRNA bins are indicated below the structures. The predicted pockets and identified functional regions are indicated by arrows. PDB code in (a, b): 3EQI. c Comparison of MEK1 PPI interfaces and CRISPR tiling identified regions. MEK1 interface for BRAF binding is highlighted as surface area in green. MEK1 homodimer interface is highlighted as surface area in blue. Drop-out screen identified regions are highlighted as surface area in red and are labelled. PDB code of BRAF-MEK1 interface: 6V2W. PDB code of MEK1-MEK1 interface: 1S9J. d MEK1-BRAF co-immunoprecipitation. IP: immunoprecipitation. WCL: whole cell lysate. e A close-up view of the MEK1-BRAF interface around the region identified at Helix EF. MEK1 protein ribbon is coloured in green, BRAF in red. MEK1 L235 residue is highlighted in cyan. f Comparison of the MEK1-BRAF interface between MEK1 wild-type and the R234_L235del variant. MEK1 wild-type protein ribbon (PDB 6V2W) is displayed in green, R234_L235del (homology model) in yellow. g Comparison of the MEK1-BRAF interface between MEK1 wild-type and the Q236_G237del variant. MEK1 wild-type protein ribbon (PDB 6V2W) is displayed in green, Q236-G237del (homology model) in pink. e–g Key residues are represented by ball-and-sticks, labelled, and indicated by arrows in the same colour as the backbone.