title: Quantitation of adenosine-5'-triphosphate used for phosphoinositide metabolism in human erythrocytes.
abstract: The human erythrocyte actively phosphorylates and dephosphorylates phosphatidylinositol present in the membrane in an apparent "futile cycle." Recent reports have proposed that this phosphorylation/dephosphorylation cycle is a significant consumer of adenosine-5'-triphosphate (ATP) in the erythrocyte. This study details two independent techniques for quantitating the ATP consumed by this phosphoinositide futile cycle. With the first technique a quasi-steady-state labeling of erythrocyte ATP with 32P-phosphate was obtained, and the rate of synthesis of 32P-phosphoinositides was then monitored. The second technique used a novel labeling strategy that allowed only ATP to be labeled with 32P; the transfer of 32P from ATP to phosphoinositides was then an independent measure of the ATP consumed for phosphoinositide synthesis. These two techniques documented that 0.5% to 1.0% of net ATP produced by the erythrocyte is used for phosphoinositide synthesis.
mesh_terms: D000255:Adenosine Triphosphate / Q000032:analysis / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D006801:Humans; D010716:Phosphatidylinositols / Q000096:biosynthesis*; D010761:Phosphorus Radioisotopes
chemical_list: D010716:Phosphatidylinositols; D010761:Phosphorus Radioisotopes; D000255:Adenosine Triphosphate