Possible role of pyrophosphate linkage in the active transport of sodium ions.
Based upon the observation that the pyrophosphate group has a greater affinity for sodium ion than for potassium ion, and that both of these ions catalyze transphosphorylation, a simple molecular mechanism is formulated for the active transport of sodium ions across biological membranes. It is assumed that the active transport takes place along a chain of phosphomonoester groups in the membrane. Pyrophosphate linkages are synthesized at the inner boundary of the membrane by a sodium-activated kinase and hydrolyzed at the outer boundary of the membrane by a potassium-activated pyrophosphatase. It is shown that in such a model the pyrophosphate linkages can diffuse across the membrane and carry sodium ions in the direction of increasing sodium ion concentration.
D001693:Biological Transport, Active; D004058:Diffusion; D011756:Diphosphates / Q000378:metabolism*; D004789:Enzyme Activation; D008566:Membranes / Q000378:metabolism*; D008954:Models, Biological; D010770:Phosphotransferases; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*
D011756:Diphosphates; D012964:Sodium; D010770:Phosphotransferases; D011188:Potassium