Localization and kinetic properties of prostaglandin E1 receptor on the plasma membrane of rabbit myometrium in late pregnancy.

The distribution of prostaglandin E1 (PGE1) receptor in various subcellular fractions of pregnant rabbit myometrium was closely related with the distribution of [Na + K]-ATPase, 5'-nucleotidase, and Ca2+-ATPase activities, marker enzymes for plasma membrane, but not with that of NADPH-cytochrome c reductase activity, which is a marker enzyme for endoplasmic reticulum. The specificity of PGE1 receptor was significantly different from those of PGE2 and PGF2 alpha. The PGE1 receptor concentration in the plasma membrane fraction increased significantly from 89.0 to 111.1 fmol/mg protein between the 28th and 30th days of pregnancy. Scatchard analysis of PGE1 receptor revealed a nonlineal plot which indicated the existence of negative cooperativity in a kinetic study.