Possible Role of Pyrophosphate Linkage in the Active Transport of Sodium Ions

AUTOR(ES)
RESUMO

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.

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