Fig. 3: Two spines of PRPK.

a The catalytic spine (C-spine) is formed by V47, V58, adenine ring of AMPPNP, L169, L170, M168, V122, L203, and F207 (from top to bottom), and it is directly anchored to the carboxyl end of the helix αF. The C-spine is well assembled. b The regulatory spine (R-spine) is formed by V101, L88, F184, and H160, and it is anchored to helix αF by a hydrogen bond between the D199 carboxyl O atom and –NH group of H160 (dashed line). The R-spine is also well organized and F184 of the DFG loop adopts an active DFG-in conformation. c Purified proteins used in the kinase assay. d In vitro kinase assay showing the regulation of PRPK autophosphorylation activity by TPRKB and OSGEP. Uncropped images of gel and autoradiograph are shown in Supplementary Fig. S6.