Essential ⍺JM and ⍺C interactions revealed through variant and structural analysis.
(A) Ensemble of 93 MET kinase domain crystal structures available in the PDB. All structures, independent of conformation, were locally aligned to JM residues 1059-1070 (all resolved JM and ⍺JM residues in orange), and ⍺C residues 1117-1134 (teal). In solid gray is a representative active structure (PDB 3R7O). Residues involved in the ⍺JM and ⍺C interface. (B) Heatmap sections of the ⍺JM and ⍺C from the MET ICD screen. (C) Distribution of alpha carbon distances for residues in the ⍺JM and ⍺C interface, shown for 63 MET crystal structures in the ensemble with residues modeled for positions 1058, 1062, 1066, 1121, 1125, 1129. Distances are independent of conformation. (D) Global alignment of inactive and active RTK kinase domain structures with resolved JM regions. (E) Residue-by-residue, backbone RMSD comparisons of inactive and active structures of MET, AXL, IR, EPHA3, KIT, and RET. (F) MuscleWS alignment of human MET and TAM family juxtamembrane helix sequences. (G) Crystal structures of MET (PDB 3R7O), RON (PDB 3PLS), and AXL (PDB 5U6B) kinase domains, with αJM (orange) and ⍺C (teal) highlighted. The inactive conformation of AXL shows an ⍺JM and ⍺C hydrophobic interaction similar to MET, but unlike MET, these interactions are slightly pivoted by an ⍺JM turn in its active conformation.