Figure 2. Structural features of Tra1.

(A) The clasp region of Tra1 is shown as part of the ring. Repeats H17, H18, H47, H48 and H49 form the clasp and contain interlocking protein loops that fix the clasp together. The view is from the front. Finger and Head regions have been removed for clarity. (B) Comparison of FRB, Kinase, LBE and FATC domains between PIKK family members. The kinase domain is split into N-lobe and C-lobe halves. Structures of Tra1, mTOR with bound ATP (PDB code 4JSP) and DNA-PKcs (PDB code 5LUQ) are indicated. The phosphate binding loop (P-loop), catalytic loop (Cat loop) and Activation loop (A-loop) are highlighted for each structure. (C) The FATC domain binds to a hydrophobic pocket. FATC is shown as a red riboon, bound to the Kinase domain shown in surface representation. Hydrophobic surfaces are coloured in yellow.

Figure 2—figure supplement 1. Figure of eight organisation of the Ring (grey), Clasp (purple, FAT (green) and FRB (orange) domains.

The juxtaposition of the Ring, Clasp, FAT and FRB domains generates two rings that form a bent ‘figure-of-eight’ conformation, where the clasp represents the crossover. Finger and KF regions have been omitted for clarity.