Structural basis for inhibitor binding to ALK2.

(A) Structure of the ALK2-K02288 complex. Inset shows the interactions of K02288 in the ATP pocket. Hydrogen bonds are shown as dotted lines. (B) ITC measurements showed ALK2 bound K02288 with KD = 7.9 nM. (C) Comparison of the binding modes of K02288 (green) and LDN-193189 (yellow) in ALK2. Both inhibitors formed hydrogen bonds to the hinge residue H286, but other interactions were divergent, including water-mediated hydrogen bonds to K235 and E248, respectively. (D) A spacefill representation of K02288 shown against a surface mesh view of the ATP pocket highlights the shape complementarity in ALK2.