The Journal of Neuroscience, November 17, 2004, ():
Time-Resolved Measurement of State-Specific P2X2 Ion Channel Cytosolic Gating Motions
J. Neurosci. Fisher et al.
24: 10475
Supplemental data
Files in this Data Supplement:
- supplemental material -
Supplementary Figure 1. Summary of FRET and electrophysiological studies.
The closed channel displays an inter fluorophore distance of ~26 Å. When ATP binds the channels open to an initial selective state (I1), but there is no detectable cytosolic conformational change. In the continued presence of ATP P2X2 channels undergo permeability changes and open to I2 with a conformational rearrangement of the cytosolic domain. Following removal of ATP the pore closes before the cytosolic domain relaxes to the resting state in ~200 s. We term this the permissive state for I2 because the pore is closed but the cytosolic domain is still in a permissive conformation, and propose that from here the channels may enter either the closed or I2 state. We cannot rule out the possibility that the permissive state may represent a component of the I2 desensitised state. The permissive state may explain why entry to the I2 state displays history-dependence as determined by electrophysiological studies (Fig 4).
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Supplemental Table
