Sodium channel protein type 5 subunit alpha (SCN5A) is a ~226 kDa protein. Pore-forming subunit of Nav1.5, a voltage-gated sodium (Nav) channel that directly mediates the depolarizing phase of action potentials in excitable membranes. Navs, also called VGSCs (voltage-gated sodium channels) or VDSCs (voltage-dependent sodium channels), operate by switching between closed and open conformations depending on the voltage difference across the membrane. In the open conformation they allow Na(+) ions to selectively pass through the pore, along their electrochemical gradient. The influx of Na(+) ions provokes membrane depolarization, initiating the propagation of electrical signals throughout cells and tissues. Nav1.5 is the predominant sodium channel expressed in myocardial cells and it is responsible for the initial upstroke of the action potential in cardiac myocytes, thereby initiating the heartbeat. 1. Gellens, ME. et al. (1992) Proceedings of the National Academy of Sciences of the United States of America 89, 554-8. PMID: 13099462. Kattygnarath, D. et al. (2011) Circulation. Cardiovascular genetics 4, 261-8. PMID: 214478244. Chakrabarti, S. et al. (2013) Circulation. Arrhythmia and electrophysiology 6, 392-401. PMID: 234208305. Gabelli, SB. et al. (2014) Nature communications 5, 5126. PMID: 253700506. Wang, L. et al. (2015) Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology 36, 2250-62. PMID: 262794307. Musa, H. et al. (2015) Proceedings of the National Academy of Sciences of the United States of America 112, 12528-33. PMID: 263925628. Kinoshita, K. et al. (2016) Heart rhythm 13, 1113-1120. PMID: 26776555 | 
