7cu3
Structure of mammalian NALCN-FAM155A complex at 2.65 angstrom
Structural highlights
FunctionNALCN_RAT Voltage-gated ion channel responsible for the resting Na(+) permeability that controls neuronal excitability. NALCN channel functions as a multi-protein complex, which consists at least of NALCN, NALF1, UNC79 and UNC80. NALCN is the voltage-sensing, pore-forming subunit of the NALCN channel complex. NALCN channel complex is constitutively active and conducts monovalent cations but is blocked by physiological concentrations of extracellular divalent cations (By similarity). In addition to its role in regulating neuronal excitability, is required for normal respiratory rhythm, systemic osmoregulation by controlling the serum sodium concentration and in the regulation of the intestinal pace-making activity in the interstitial cells of Cajal. NALCN channel is also activated by neuropeptides such as neurotensin and substance P (SP) through a SRC family kinases-dependent pathway. In addition, NALCN activity is enhanced/modulated by several GPCRs, such as CHRM3 (By similarity).[UniProtKB:Q8BXR5][UniProtKB:Q8IZF0] Publication Abstract from PubMedResting membrane potential determines the excitability of the cell and is essential for the cellular electrical activities. The NALCN channel mediates sodium leak currents, which positively adjust resting membrane potential towards depolarization. The NALCN channel is involved in several neurological processes and has been implicated in a spectrum of neurodevelopmental diseases. Here, we report the cryo-EM structure of rat NALCN and mouse FAM155A complex to 2.7 A resolution. The structure reveals detailed interactions between NALCN and the extracellular cysteine-rich domain of FAM155A. We find that the non-canonical architecture of NALCN selectivity filter dictates its sodium selectivity and calcium block, and that the asymmetric arrangement of two functional voltage sensors confers the modulation by membrane potential. Moreover, mutations associated with human diseases map to the domain-domain interfaces or the pore domain of NALCN, intuitively suggesting their pathological mechanisms. Structure of voltage-modulated sodium-selective NALCN-FAM155A channel complex.,Kang Y, Wu JX, Chen L Nat Commun. 2020 Dec 3;11(1):6199. doi: 10.1038/s41467-020-20002-9. PMID:33273469[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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