Receptors for E type prostaglandins in the plasma membrane of nonpregnant human myometrium.

Binding sites for prostaglandin E₁ were present in the 1000g supernatant of nonpregnant human myometrium. When the 1000g supernatant was fractionated the distribution of prostaglandin E₁ binding sites followed that of the plasma membrane markers, phosphodiesterase-I and 5′-nucleotidase, but was different from that of the endoplasmic reticulum marker NADPH-cytochrome c reductase or the mitochondrial marker succinatecytochrome c reductase. It is concluded that a major portion of the prostaglandin E₁ receptors in the human myometrium is located at the plasma membrane. Scatchard analysis of prostaglandin E₁ binding to the plasma membrane-enriched fraction indicated the presence of both high and low affinity sites.