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. 2010 Aug 4;99(3):798–807. doi: 10.1016/j.bpj.2010.05.008

Figure 6.

Figure 6

Maps and histograms of range-energy and Φ in the α-subunit extracellular domain. (A) The range-energy is the natural logarithm of the largest/smallest gating equilibrium constant ratio for a family of mutations at each position. Blue spheres: ≥4.0 kcal/mol; ∗ the approximate position of the agonist. The largest range-energy residues approximately form a column that links the transmitter-binding site (αW149) and the gate region of the pore-lining M2 helix (αV255). Bottom: Histogram of range-energy for all of the residues studied so far in the α-subunit. Residues in the marked bins: 1), W149, V261, S266, and I274; 2), V132, I264, and F135; 3), S268 and P265; 4), V255 and P272; and 5), E45. (B) Φ is the slope of the R/E relationship. Residues in the α-subunit with a range-energy >1.5 kcal/mol are shown as spheres. Color is according to the Φ-value in the histogram (for clarity, residues with Φ < 0.5 are not shown). αA96 and αP272 are surrounded by higher-Φ elements. αA96, αY127, and αE45 have similar Φ-values.