Figure 6.

Modeling the nSLD profile for the activated, open state of KvAP in a hydrated POPC bilayer membrane. The nSLD profiles for the membranes in (A) and (B) below are at negative contrast relative to 90–100% D₂O. (A) Left side shows the experimental nSLD(z) profile for the KvAP-POPC membrane at a contrast of 90% D₂O/10% H₂O (gray) compared with that of the resolution-limited model based on MD simulation for the Kv1.2/2.1 chimera channel within a hydrated, POPC bilayer at a contrast of 100% D₂O (black) at twice the spatial resolution of the experimental profile. The two arrows point out the “double-well” shape of the experimental nSLD(z) profile. (A) Right side shows the separate contributions of the Kv1.2/2.1 protein (dashed) and the POPC bilayer (dotted) in 100% D₂O to the model profile and their sum (solid). (B) Left side shows the experimental nSLD(z) profile for the KvAP-POPC membrane at a contrast of 90% D₂O/10% H₂O (gray) compared with that of the resolution-limited model based on MD simulation of an improved model for this state of the KvAP channel within a hydrated, POPC bilayer at a contrast of 100% D₂O (black) at twice the spatial resolution of the experimental profile. (B) Right side shows the separate contributions of the KvAP protein (dashed) and the POPC bilayer (dotted) in 100% D₂O to the model profile, and their sum (solid). Juxtaposed below, we show to scale a rendering of an instantaneous configuration of the KvAP protein (black ribbon) embedded with the POPC bilayer (gray licorice) in a water slab (white shaded) from the MD simulation of the improved model for this state of the KvAP channel.