Phosphate modulation of calcium transport by a calcium-phospholipid-phosphate complex of calcifying tissues.
The ionophoretic activities of a stable Ca-PS-Pi complex were examined in a three-compartment lipid-aqueous phase transport system. It was found that the complex transported Ca2+ at a slower rate than free PS. Analysis of the transport process, using an equilibrium partitioning model, revealed that Ca2+ binding to the complex was the rate-limiting step. This inhibition was overcome by the addition of exogeneous Pi. It was concluded that the complex acted as an ionophore and that the presence of coordinated Ca and P atoms facilitated Pi modulation of Ca2+ transport.
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002113:Calcification, Physiologic; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D007476:Ionophores / Q000378:metabolism; D010710:Phosphates / Q000494:pharmacology*; D010743:Phospholipids / Q000378:metabolism*
D007476:Ionophores; D010710:Phosphates; D010743:Phospholipids; D002118:Calcium