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.