Fig. 6: Allosteric site occupancy and conformational changes.

a State-I tetramer shown in surface representation, view onto the AC Dimer-2 coloured as in Fig. 1. The nucleotides bound at the allosteric sites are shown in stick representation, the allosteric site formed at the interface of Monomer-A -B -C (ABC) is boxed. Allosteric site ABC in (b) State-I, (c) State-II, (d) State-III, (e) State-IV and (f) State-V tetramers. Views are rotated 90° with respect to the box orientation in (a). In each panel the protein backbone is shown in cartoon representation, residues from N-terminal catalytic domains and C-terminal regulatory domains are coloured as in Fig. 1. The bound AL1 GTP (yellow) and AL2 dATP (cyan) nucleotides and selected allosteric site residues are shown in stick representation, Mg ions as green spheres.