| Structural highlights
Disease
[SCN2B_HUMAN] Familial atrial fibrillation. The disease is caused by mutations affecting the gene represented in this entry. Genetic variations in SCN2B may be involved in Brugada syndrome (PubMed:23559163). This tachyarrhythmia is characterized by right bundle branch block and ST segment elevation on an electrocardiogram (ECG). It can cause the ventricles to beat so fast that the blood is prevented from circulating efficiently in the body. When this situation occurs, the individual will faint and may die in a few minutes if the heart is not reset.[1] [SCN2A_HUMAN] Defects in SCN2A are the cause of seizures, benign familial infantile type 3 (BFIS3) [MIM:607745]. An autosomal dominant disorder in which afebrile seizures occur in clusters during the first year of life, without neurologic sequelae.[2] [3] [4] [5] Defects in SCN2A are the cause of epileptic encephalopathy early infantile type 11 (EIEE11) [MIM:613721]. EIEE11 is an autosomal dominant seizure disorder characterized by infantile onset of refractory seizures with resultant delayed neurologic development and persistent neurologic abnormalities.[6] [7]
Function
[SCN2B_HUMAN] Crucial in the assembly, expression, and functional modulation of the heterotrimeric complex of the sodium channel. The subunit beta-2 causes an increase in the plasma membrane surface area and in its folding into microvilli. Interacts with TNR may play a crucial role in clustering and regulation of activity of sodium channels at nodes of Ranvier (By similarity). [CM3A_CONKI] Mu-conotoxins block voltage-gated sodium channels (Nav). This toxin potently blocks rNav1.2/SCN2A and rNav1.4/SCN4A. It also moderately blocks rNav1.1/SCN1A, rNav1.3/SCN3A, rNav1.5/SCN5A, mNav1.6/SCN8A, and rNav1.7/SCN9A. On rNav1.2/SCN2A, it produces a block that is only partially reversible. The block of SCN9A is modified when beta-subunits are coexpressed with the alpha subunit. Hence, blocks of channels containing beta-1 and beta-3 subunits are more potent (compared to channels without beta subunits), whereas blocks of channels containing beta-2 and beta-4 subunits are less potent (compared to channels without beta subunits).[8] [9] [10] [11] [12] [13] [14] [SCN2A_HUMAN] Mediates the voltage-dependent sodium ion permeability of excitable membranes. Assuming opened or closed conformations in response to the voltage difference across the membrane, the protein forms a sodium-selective channel through which Na(+) ions may pass in accordance with their electrochemical gradient.
Publication Abstract from PubMed
The voltage-gated sodium channel Nav1.2 is responsible for the initiation and propagation of action potentials in the central nervous system. We report the cryo-electron microscopy structure of human Nav1.2 bound to a peptidic pore blocker, the mu-conotoxin KIIIA, in the presence of an auxiliary subunit beta2 to an overall resolution of 3.0 A. The immunoglobulin (Ig) domain of beta2 interacts with the shoulder of the pore domain through a disulfide bond. The 16-residue KIIIA interacts with the extracellular segments in repeats I to III, placing Lys7 at the entrance to the selectivity filter. Many interacting residues are specific to Nav1.2, revealing a molecular basis for KIIIA specificity. The structure establishes a framework for rational design of subtype-specific blockers for Nav channels.
Molecular basis for pore blockade of human Na(+) channel Nav1.2 by the mu-conotoxin KIIIA.,Pan X, Li Z, Huang X, Huang G, Gao S, Shen H, Liu L, Lei J, Yan N Science. 2019 Feb 14. pii: science.aaw2999. doi: 10.1126/science.aaw2999. PMID:30765605[15]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Riuro H, Beltran-Alvarez P, Tarradas A, Selga E, Campuzano O, Verges M, Pagans S, Iglesias A, Brugada J, Brugada P, Vazquez FM, Perez GJ, Scornik FS, Brugada R. A missense mutation in the sodium channel beta2 subunit reveals SCN2B as a new candidate gene for Brugada syndrome. Hum Mutat. 2013 Jul;34(7):961-6. doi: 10.1002/humu.22328. Epub 2013 Apr 29. PMID:23559163 doi:http://dx.doi.org/10.1002/humu.22328
- ↑ Sugawara T, Tsurubuchi Y, Agarwala KL, Ito M, Fukuma G, Mazaki-Miyazaki E, Nagafuji H, Noda M, Imoto K, Wada K, Mitsudome A, Kaneko S, Montal M, Nagata K, Hirose S, Yamakawa K. A missense mutation of the Na+ channel alpha II subunit gene Na(v)1.2 in a patient with febrile and afebrile seizures causes channel dysfunction. Proc Natl Acad Sci U S A. 2001 May 22;98(11):6384-9. PMID:11371648 doi:10.1073/pnas.111065098
- ↑ Heron SE, Crossland KM, Andermann E, Phillips HA, Hall AJ, Bleasel A, Shevell M, Mercho S, Seni MH, Guiot MC, Mulley JC, Berkovic SF, Scheffer IE. Sodium-channel defects in benign familial neonatal-infantile seizures. Lancet. 2002 Sep 14;360(9336):851-2. PMID:12243921 doi:10.1016/S0140-6736(02)09968-3
- ↑ Berkovic SF, Heron SE, Giordano L, Marini C, Guerrini R, Kaplan RE, Gambardella A, Steinlein OK, Grinton BE, Dean JT, Bordo L, Hodgson BL, Yamamoto T, Mulley JC, Zara F, Scheffer IE. Benign familial neonatal-infantile seizures: characterization of a new sodium channelopathy. Ann Neurol. 2004 Apr;55(4):550-7. PMID:15048894 doi:10.1002/ana.20029
- ↑ Liao Y, Deprez L, Maljevic S, Pitsch J, Claes L, Hristova D, Jordanova A, Ala-Mello S, Bellan-Koch A, Blazevic D, Schubert S, Thomas EA, Petrou S, Becker AJ, De Jonghe P, Lerche H. Molecular correlates of age-dependent seizures in an inherited neonatal-infantile epilepsy. Brain. 2010 May;133(Pt 5):1403-14. doi: 10.1093/brain/awq057. Epub 2010 Apr 5. PMID:20371507 doi:10.1093/brain/awq057
- ↑ Ogiwara I, Ito K, Sawaishi Y, Osaka H, Mazaki E, Inoue I, Montal M, Hashikawa T, Shike T, Fujiwara T, Inoue Y, Kaneda M, Yamakawa K. De novo mutations of voltage-gated sodium channel alphaII gene SCN2A in intractable epilepsies. Neurology. 2009 Sep 29;73(13):1046-53. doi: 10.1212/WNL.0b013e3181b9cebc. PMID:19786696 doi:10.1212/WNL.0b013e3181b9cebc
- ↑ Liao Y, Anttonen AK, Liukkonen E, Gaily E, Maljevic S, Schubert S, Bellan-Koch A, Petrou S, Ahonen VE, Lerche H, Lehesjoki AE. SCN2A mutation associated with neonatal epilepsy, late-onset episodic ataxia, myoclonus, and pain. Neurology. 2010 Oct 19;75(16):1454-8. doi: 10.1212/WNL.0b013e3181f8812e. PMID:20956790 doi:10.1212/WNL.0b013e3181f8812e
- ↑ Bulaj G, West PJ, Garrett JE, Watkins M, Zhang MM, Norton RS, Smith BJ, Yoshikami D, Olivera BM. Novel conotoxins from Conus striatus and Conus kinoshitai selectively block TTX-resistant sodium channels. Biochemistry. 2005 May 17;44(19):7259-65. PMID:15882064 doi:http://dx.doi.org/10.1021/bi0473408
- ↑ Zhang MM, Green BR, Catlin P, Fiedler B, Azam L, Chadwick A, Terlau H, McArthur JR, French RJ, Gulyas J, Rivier JE, Smith BJ, Norton RS, Olivera BM, Yoshikami D, Bulaj G. Structure/function characterization of micro-conotoxin KIIIA, an analgesic, nearly irreversible blocker of mammalian neuronal sodium channels. J Biol Chem. 2007 Oct 19;282(42):30699-706. Epub 2007 Aug 27. PMID:17724025 doi:http://dx.doi.org/10.1074/jbc.M704616200
- ↑ Holford M, Zhang MM, Gowd KH, Azam L, Green BR, Watkins M, Ownby JP, Yoshikami D, Bulaj G, Olivera BM. Pruning nature: Biodiversity-derived discovery of novel sodium channel blocking conotoxins from Conus bullatus. Toxicon. 2009 Jan;53(1):90-8. doi: 10.1016/j.toxicon.2008.10.017. Epub 2008 Nov, 20. PMID:18950653 doi:http://dx.doi.org/10.1016/j.toxicon.2008.10.017
- ↑ Wilson MJ, Yoshikami D, Azam L, Gajewiak J, Olivera BM, Bulaj G, Zhang MM. mu-Conotoxins that differentially block sodium channels NaV1.1 through 1.8 identify those responsible for action potentials in sciatic nerve. Proc Natl Acad Sci U S A. 2011 Jun 21;108(25):10302-7. doi:, 10.1073/pnas.1107027108. Epub 2011 Jun 7. PMID:21652775 doi:http://dx.doi.org/10.1073/pnas.1107027108
- ↑ McArthur JR, Singh G, McMaster D, Winkfein R, Tieleman DP, French RJ. Interactions of key charged residues contributing to selective block of neuronal sodium channels by mu-conotoxin KIIIA. Mol Pharmacol. 2011 Oct;80(4):573-84. doi: 10.1124/mol.111.073460. Epub 2011 Jun , 27. PMID:21709136 doi:http://dx.doi.org/10.1124/mol.111.073460
- ↑ Van Der Haegen A, Peigneur S, Tytgat J. Importance of position 8 in mu-conotoxin KIIIA for voltage-gated sodium channel selectivity. FEBS J. 2011 Sep;278(18):3408-18. doi: 10.1111/j.1742-4658.2011.08264.x. Epub, 2011 Aug 24. PMID:21781281 doi:http://dx.doi.org/10.1111/j.1742-4658.2011.08264.x
- ↑ Zhang MM, Wilson MJ, Azam L, Gajewiak J, Rivier JE, Bulaj G, Olivera BM, Yoshikami D. Co-expression of Na(V)beta subunits alters the kinetics of inhibition of voltage-gated sodium channels by pore-blocking mu-conotoxins. Br J Pharmacol. 2013 Apr;168(7):1597-610. doi: 10.1111/bph.12051. PMID:23146020 doi:http://dx.doi.org/10.1111/bph.12051
- ↑ Pan X, Li Z, Huang X, Huang G, Gao S, Shen H, Liu L, Lei J, Yan N. Molecular basis for pore blockade of human Na(+) channel Nav1.2 by the mu-conotoxin KIIIA. Science. 2019 Feb 14. pii: science.aaw2999. doi: 10.1126/science.aaw2999. PMID:30765605 doi:http://dx.doi.org/10.1126/science.aaw2999
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