Fig. 1

Structural comparison of human CLKs. a Domain structures of human CLK1, -2, -3, and -4. b Crystal structure of human CLK1 without N-terminus domain (PDB ID: 6I5H). The protein structure backbone is visualized as a cartoon representation, while the ligand and its interacting residues are visualized as sticks. H-bonds are shown as black dashed lines. The coloring of all domains and signature sequence motifs are consistent with panel a. c Structural superposition of CLK1 (PDB ID: 6I5H, green), CLK2 (PDB ID: 6KHE, cyan), CLK3 (PDB ID: 2EU9, magenta) and CLK4 (PDB ID: 6FYV, yellow). The protein structural backbone is represented as a ribbon. d Electrostatic surface representation of CLKs. The blue and red colors represent positive and negative charges, respectively. The different pockets among these kinases were determined by the distances between side chains of conserved Val residue in the N-lobe and DFG-1 residue in the C-lobe