|
Figure 3.
Stabilization of the selectivity filter and tetramer
conformation in WSK3 by a network of salt bridges and hydrogen
bonds. Important side chains are depicted in the licorice
representation, with hydrogen bonds indicated by red dashed
lines. (A and B) The same region is depicted from different
viewing angles. (C) Quaternary relationship among W46, W47, E50,
Y57, and R68 in WSK3. W67 and W68 in KcsA are shown in black
lines for comparison. (D) Comparison of the selectivity filter
between WSK3 structure and KcsA crystal structures obtained in
the presence of high (1K4C) and low (1K4D) K^+ concentrations.
WSK3 is depicted in thick sticks and KcsA in thin lines. Element
colors: C, gray; N, blue; O, red; and K, yellow. K^+ locations
are taken from the crystal structures and not from the NMR data.
|
