6vrr | pdb_00006vrr
Crystal structure of a disease mutant of the Voltage-gated Sodium Channel Beta 2 subunit extracellular domain
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] 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). Publication Abstract from PubMedBackground: Voltage-gated sodium (NaV) channels help regulate electrical activity of the plasma membrane. Mutations in associated subunits can result in pathological outcomes. Here we examined the interaction of NaV channels with cardiac arrhythmia-linked mutations in SCN2B and SCN4B, two genes that encode auxiliary beta-subunits. Materials and Methods: To investigate changes in SCN2B (R137H) and SCN4B (I80T) function, we combined three-dimensional X-ray crystallography with electrophysiological measurements on NaV1.5, the dominant subtype in the heart. Results: SCN4B (I80T) alters channel activity, whereas SCN2B (R137H) does not have an apparent effect. Structurally, the SCN4B (I80T) perturbation alters hydrophobic packing of the subunit with major structural changes and causes a thermal destabilization of the folding. In contrast, SCN2B (R137H) leads to structural changes but overall protein stability is unaffected. Conclusion: SCN4B (I80T) data suggest a functionally important region in the interaction between NaV1.5 and beta4 that, when disrupted, could lead to channel dysfunction. A lack of apparent functional effects of SCN2B (R137H) on NaV1.5 suggests an alternative working mechanism, possibly through other NaV channel subtypes present in heart tissue. Indeed, mapping the structural variations of SCN2B (R137H) onto neuronal NaV channel structures suggests altered interaction patterns. Biophysical Investigation of Sodium Channel Interaction with beta-Subunit Variants Associated with Arrhythmias.,Llongueras JP, Das S, De Waele J, Capulzini L, Sorgente A, Van Petegem F, Bosmans F Bioelectricity. 2020 Sep 1;2(3):269-278. doi: 10.1089/bioe.2020.0030. Epub 2020, Sep 16. PMID:34476357[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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