6wbm | pdb_00006wbm
Cryo-EM structure of human Pannexin 1 channel N255A mutant
Structural highlights
Function[PANX1_HUMAN] Structural component of the gap junctions and the hemichannels. May play a role as a Ca(2+)-leak channel to regulate ER Ca(2+) homeostasis.[1] [2] Publication Abstract from PubMedPannexin 1 (PANX1) is an ATP-permeable channel with critical roles in a variety of physiological functions such as blood pressure regulation(1), apoptotic cell clearance(2) and human oocyte development(3). Here we present several structures of human PANX1 in a heptameric assembly at resolutions of up to 2.8 angstrom, including an apo state, a caspase-7-cleaved state and a carbenoxolone-bound state. We reveal a gating mechanism that involves two ion-conducting pathways. Under normal cellular conditions, the intracellular entry of the wide main pore is physically plugged by the C-terminal tail. Small anions are conducted through narrow tunnels in the intracellular domain. These tunnels connect to the main pore and are gated by a long linker between the N-terminal helix and the first transmembrane helix. During apoptosis, the C-terminal tail is cleaved by caspase, allowing the release of ATP through the main pore. We identified a carbenoxolone-binding site embraced by W74 in the extracellular entrance and a role for carbenoxolone as a channel blocker. We identified a gap-junction-like structure using a glycosylation-deficient mutant, N255A. Our studies provide a solid foundation for understanding the molecular mechanisms underlying the channel gating and inhibition of PANX1 and related large-pore channels. Structures of human pannexin 1 reveal ion pathways and mechanism of gating.,Ruan Z, Orozco IJ, Du J, Lu W Nature. 2020 Jun 3. pii: 10.1038/s41586-020-2357-y. doi:, 10.1038/s41586-020-2357-y. PMID:32494015[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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