Journal
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volume 105, Issue 33, Pages 12063-12068Publisher
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0803008105
Keywords
gating; imaging; purinergic
Categories
Funding
- Human Frontier Science Program
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ATP-gated P2X receptors display ion permeability increases within seconds of receptor activation as the channels enter the I-2 state, which is permeable to organic cations and dye molecules. The mechanisms underlying this important behavior are not completely understood. In one model, the I-2 state is thought to be due to opening of Pannexin-1 (Panx-1) channels, and, in the second, it is thought to be an intrinsic P2X property. We tested both models by measuring ion and dye permeability and used a patch-clamp coordinated spectroscopy approach to measure conformational changes. Our data show that Panx-1 channels make no detectable contribution to the P2X(2) receptor I-2 state. However, P2X2 receptors display permeability dynamics, which are correlated with conformational changes in the cytosolic domain remote from the selectivity filter itself. Finally, the data illustrate the utility of a new approach, using tetracysteine tags and biarsenical fluorophores to measure site-specific conformational changes in membrane proteins.
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