Fig. 1.
KvAP structures are in similar conformations with and without Fv fragments. (a) Four-fold averaged electron density map (1.0 σ) of KvAP at 8 Å calculated with (2 Fo - Fc) Fourier coefficients with the voltage sensor omitted. Two KvAP pores were used to calculate the map. The α-carbon traces of the KvAP structure (dark brown) were generated by superposition of the KvAP-Fv complex structure onto the KvAP pore molecular replacement solutions. (b) Contacts in the KvAP crystal. A layer of channel molecules is formed by lateral packing of voltage sensors with neighboring channel molecules within a layer and end-to-end packing between layers. Two channels (red), surrounded by black lines, define the unit cell. (c) Native sharpened 2-fold averaged electron density map (1.0 σ) of the KvAP-33H1 Fv complex at 3.9 Å calculated with Fo Fourier coefficients. Combined phases (single isomorphous replacement with anomalous scattering and partial molecular replacement phases) were used for map calculation. The α-carbon traces of the KvAP-Fv structure were colored dark brown. (d) Crystal packing in the KvAP-33H1 Fv crystal as viewed down the crystallographic 4-fold axis. Channels are colored blue, and Fv fragments are colored green. Four channels and 16 Fvs, surrounded by black lines, comprise a unit cell.