1.A.65.1.2
The SARS coronavirus pore-forming envelope (E) protein or protein 3a (76 aas; 1 TMS) forms a pentameric cation-selective pore (Torres et al. 2006; Scott and Griffin 2015) that binds amantadine (Torres et al., 2007). A single polar residue and distinct membrane topologies impact its function (Ruch and Machamer, 2012).  The E protein ion channel (IC) activity is cation-specific and K⁺-selective and is specifically correlated with enhanced pulmonary damage, edema accumulation and death.  Calcium ions together with pH modulated E protein pore charge and selectivity (Nieto-Torres et al. 2015). There is a single transmembrane domain in E, suggesting an allosteric interaction between extramembrane and transmembrane domains (To et al. 2016).