Abstract: | Pretreatment of membranes for 1 hr at 4° with up to 0.1% Triton X-100 (TX-100) and sodium desoxycholate (SDC), resulted in a greater loss of 3H] prostaglandin (PG)F2α binding compared to E1 binding. Lubrol WX (LWX) tended to cause a greater loss of 3H]PGF2α than E1 binding. However, the differential loss was not as marked as with TX-100 or SDC. Triton X-305 was relatively ineffective, but loss of 3H]PGE1 binding was greater than for PGF2α. Increasing concentrations of dimethylsulfoxide (DMSO) progressively inhibited PGF2α binding without affecting PGE1 binding. The detergent, but not DMSO, induced losses of membrane PG binding were due to solubilization of the receptors. Greater amounts of membrane protein and phospholipids were solubilized at detergent (TX-100 and SDC) concentrations that solubilized 100% of PGE1 receptors compared to 100% solubilization of F2α receptors. Neither the duration of preincubation nor the amount of membrane protein chosen were responsible for differential PGE1 and F2α receptor losses. These differential membrane PG receptor losses raise the possibility of differences in PGE1 and F2α receptors association with the membrane structure. |