The Proton Selective Ion Channels of Influenza A and B Viruses
Robert A. Lamb and Lawrence H. Pinto
from: Influenza Virology: Current Topics (Edited by: Yoshihiro Kawaoka). Caister Academic Press, U.K. (2006)
Influenza A and B viruses each encode via very different coding strategies a small oligomeric integral membrane protein, M2 of influenza A virus and BM2 of influenza B virus, and each protein is a proton selective ion channel. M2 and BM2 proteins have very different amino acid sequences but they share two key amino acid residues in the channel pore, a histidine and a tryptophan. These two residues provide a model of elegant simplicity for ionic selectivity and gating of these minimalistic ion channels. The activity of the ion channels are required during virus uncoating in the acidic environment of the endosome, to permit acidification of the interior of the virion particle which brings about protein-protein dissociation. The ion channels also equilibrate the acidic pH of the lumen of the trans Golgi network with the cytoplasm, during their own transport through the exocytic pathway. The influenza A virus M2 ion channel protein is the target of the antiviral drug amantadine ad the drug blocks directly ion channel activity. Thus, once the atomic structures of the M2 and BM2 ion channel proteins are known, it makes the channels attractive targets for rational drug design. The M2 and BM2 ion channel proteins may be multifunctional as the available data suggests the M2 cytoplasmic tail is involved in influenza virus assembly read more ...