Figure 9
Molecular modeling of Gα subunits and the predicted conformational changes of the β2/β3 loop. (A) Left: A molecular model of Gα16 is depicted with the helical and GTPase domains highlighted in indigo and dark slate grey, respectively. Regions colored in yellow are the surface-exposing secondary structures that interact with PLCβ, while the TPR1-interacting β3 strand is in magenta. Right: The model is turned 90° clockwise horizontally to show the highlighted residues on α3 helix and the β2-β3 loop in a different orientation. (B) Models of Gαz (white) and N200-C164 (magenta) for the predicted conformational changes by mutating the β2-β3 loop of Gαz are depicted in tube-like carbon backbone. Side chains of the residues are colored according to the root mean square deviations (RMSD) between these residues on the two models. Blue and red colors represent the least and greatest deviations, respectively. The scale bar shows the corresponding RMSD range. (C) The β2-β3 loop of Gαz and N200-C164 are shown in the same orientations as in (B) but with the carbon backbone, side chains and the accessible molecular surfaces in the same colors to visualize the overall deviations in molecular surfaces and volumes caused by the mutations.