6bwi | pdb_00006bwi
3.7 angstrom cryoEM structure of full length human TRPM4
Structural highlights
DiseaseTRPM4_HUMAN Familial progressive cardiac conduction defect;Brugada syndrome. The disease is caused by mutations affecting the gene represented in this entry. FunctionTRPM4_HUMAN Calcium-activated non selective (CAN) cation channel that mediates membrane depolarization. While it is activated by increase in intracellular Ca(2+), it is impermeable to it. Mediates transport of monovalent cations (Na(+) > K(+) > Cs(+) > Li(+)), leading to depolarize the membrane. It thereby plays a central role in cadiomyocytes, neurons from entorhinal cortex, dorsal root and vomeronasal neurons, endocrine pancreas cells, kidney epithelial cells, cochlea hair cells etc. Participates in T-cell activation by modulating Ca(2+) oscillations after T lymphocyte activation, which is required for NFAT-dependent IL2 production. Involved in myogenic constriction of cerebral arteries. Controls insulin secretion in pancreatic beta-cells. May also be involved in pacemaking or could cause irregular electrical activity under conditions of Ca(2+) overload. Affects T-helper 1 (Th1) and T-helper 2 (Th2) cell motility and cytokine production through differential regulation of calcium signaling and NFATC1 localization. Enhances cell proliferation through up-regulation of the beta-catenin signaling pathway.[1] [2] [3] [4] [5] [6] [7] [8] Publication Abstract from PubMedTransient receptor potential melastatin subfamily member 4 (TRPM4) is a widely distributed, calcium-activated, monovalent-selective cation channel. Mutations in human TRPM4 (hTRPM4) result in progressive familial heart block. Here, we report the electron cryomicroscopy structure of hTRPM4 in a closed, Na(+)-bound, apo state at pH 7.5 to an overall resolution of 3.7 A. Five partially hydrated sodium ions are proposed to occupy the center of the conduction pore and the entrance to the coiled-coil domain. We identify an upper gate in the selectivity filter and a lower gate at the entrance to the cytoplasmic coiled-coil domain. Intramolecular interactions exist between the TRP domain and the S4-S5 linker, N-terminal domain, and N and C termini. Finally, we identify aromatic interactions via pi-pi bonds and cation-pi bonds, glycosylation at an N-linked extracellular site, a pore-loop disulfide bond, and 24 lipid binding sites. We compare and contrast this structure with other TRP channels and discuss potential mechanisms of regulation and gating of human full-length TRPM4. , PMID:29463718[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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