Consider a transmembrane protein that forms a hydrophilic pore across the plasma membrane of a eukaryotic cell,
allowing Na+ to enter the cell when it is activated upon binding a specific ligand on its extracellular side. It is made of five similar transmembrane subunits, each containing a membrane-spanning α helix with hydrophilic amino acid side chains on one surface of the helix and hydrophobic amino acid side chains on the opposite surface. Considering the function of the protein as a channel for Na+ ions to enter the cell, propose a possible arrangement of the seven membrane-spanning α helices in the membrane.
The sevenmembrane-spanning helices of the channel for sodium ions are arranged in such a way that Hydrophobic amino... View the full answer