Sodium-dependent and sodium-independent phosphate uptake by full-grown, prophase-arrested oocytes of Xenopus laevis before and after progesterone-induced maturation.

The uptake of inorganic phosphate by full-grown, prophase-arrested oocytes occurs by two essentially independent transport systems, which accomplish the delivery of extracellular phosphate into two different cellular compartments. One transport system is sodium-dependent, the other is sodium-independent. Both systems can be inhibited by sulfhydryl reagents and the sodium-dependent system becomes inhibited during progesterone-induced oocyte maturation.