Figure 4.

TGFβ receptor kinase domain. Structure of Alk5 kinase domain in complex with FKBP12. Key structural features are colored and labeled, L45 loop (green), GS domain (orange), aC helix (blue), activation loop (red), FKBP12 (dark gray). N-terminal (N-lobe), and C-terminal (C-lobe) lobes are labeled to the left. Inlet shows the conformational changes made to two salt bridges in Alk5 either bound (light gray) or unbound (tan) to FKBP12. (A color version of this figure is available in the online journal.)