Figure 1.

(A) Topology diagrams depicting the major divisions of the P-loop NTPases and accompanying cladogram depicting higher-order relationships. The cladogram depicts the two major divisions: the kinase-GTPase (KG) division and the ASCE (The additional strand, catalytic E division) division. Strands and helices forming the core of ASCE P-Loop NTPase domain are numbered and colored. Core strands and helices are in orange and grey-white, respectively, with central strand S4 in yellow. Synapomorphies shared across different lineages are colored violet, elements not conserved across lineages are colored gray and outlined in dotted lines. Abbreviations: WA, Walker A; WB, Walker B and Sen1, sensor-1. (B) Topology diagrams depicting the structural developments in the evolution of ABC ATPases. The elaborations of the insert regions are depicted.