maleic-acid and acetic-anhydride

The sarcoplasmic reticulum (SR) of skeletal muscle contains a Pi transporter which transports Pi into the lumen of the SR, increasing the level of accumulation of Ca2+ by SR by forming insoluble salts with Ca2+. Phosphonocarboxylic acids inhibit the transport of Pi by the transporter, phosphonoformic acid itself being transported into the SR increasing the level of accumulation of Ca2+. Phenylphosphonic acid also inhibits Pi transport, distinguishing the Pi transporter of SR from the Na+/Pi transporter of brush-border membranes. Oxalate transport is also inhibited by the phosphono-carboxylic acids, consistent with the suggestion that oxalate and phosphate are carried on the same transporter. The effects of maleate are, however, not inhibited, suggesting a separate carrier for the dicarboxylic acids. Acetic anhydride and phenylglyoxal inhibit the transporter, Pi providing protection against the effects of acetic anhydride, suggesting the presence of a lysine residue at the Pi binding site. ATP provides protection against the effects of acetic anhydride and phenylglyoxal, suggesting the presence of an ATP binding site on the transporter.

Topics: Acetic Anhydrides; Adenosine Triphosphatases; Animals; Binding Sites; Biological Transport; Calcium; Carrier Proteins; Female; Foscarnet; Maleates; Membrane Proteins; Muscles; Phenylglyoxal; Phosphate-Binding Proteins; Phosphates; Phosphonoacetic Acid; Rabbits; Sarcoplasmic Reticulum; Succinates; Succinic Acid