Shuttling Bicarbonate In And Out Of Cells

Small aromatic molecules have been shown to transport bicarbonate anions (HCO₃^–) across lipid membranes, a finding that could open new areas of biomembrane research and may point to new medicines (Nat. Chem., DOI: 10.1038/nchem.178). Bicarbonate plays important roles in biology, including acting as a biochemical buffer. Membrane-embedded proteins ferry bicarbonate in and out of cells, and problems with this transport system can lead to heart disease, cystic fibrosis, and other conditions. To date, though, researchers have uncovered few molecular details about how these transport proteins selectively shuttle bicarbonate across the cell membrane. To learn more, a team led by Jeffery T. Davis of the University of Maryland; Philip A. Gale of the University of Southampton, in England; and Roberto Quesada of the University of Burgos, in Spain, searched for chemical mediators of bicarbonate transport. Through NMR experiments and measurements with ion-selective electrodes, they demonstrated that prodigiosin, a tripyrrole microbial natural product, promotes the exchange of chloride anion for bicarbonate anion across synthetic lipid membranes. Synthetic transporters also facilitate the exchange, but not as efficiently as prodigiosin does, the researchers found.