Desensitization of prostaglandin receptors

我们研究了前列腺素E_1和l_2（前列腺环素）受体脱敏的机制。用[^3H] PGE_1在37℃下预孵育60 min。即使在GTPgammaS存在的情况下，配体与受体的解离也显著减少。稳定的[^3H] pge_1结合受体配合物用6%洋地黄苷溶解。溶解后的[^3H]PGE_1受体用Ultrogel AcA44柱[^<35>S]GTPgammaS结合活性洗脱。同时含有[^3H]PGE_1和[^<35>S]GTPgammaS结合活性的组分进一步通过小麦胚芽凝集素(WGA)-琼脂糖和苯基- sepharose CL-4B的柱层析纯化。部分纯化的[^3H] pge_1结合受体用[^<14>C]5′- p -氟磺酰基苯甲酰鸟苷进行亲和标记，检测到分子量为60 kDa的蛋白。伊洛前列素是一种稳定的前列环素类似物，可瞬间刺激腺苷酸环化酶活性。floprost还诱导刺激鸟嘌呤核苷酸结合蛋白（Gsalpha）的α亚基（42-和45-kDa）从膜转移到细胞质。综上所述，前列腺素受体的脱敏是由前列腺素E_1和前列腺环素的不同机制引起的。

We have investigated the mechanism of desensitization of receptors for prostaglandin E_1 and for l_2 (prostacyclin). When the membranes were preincubated with[ ^3H] PGE_1 for 60 min at 37ﾟC. the dissociation of the ligand form the receptor was remarkably decreased, even in the presence of GTPgammaS. The stable[ ^3H]PGE_1-bound receptor complex was solubilized with 6% digitonin. The solubilized[ ^3H]PGE_1 receptor was eluted with[ ^<35>S]GTPgammaS binding activity from an Ultrogel AcA44 column. The fractions containing activities of both[ ^3H]PGE_1 and[ ^<35>S]GTPgammaS bindings were further purified by column chromatographies on wheat germ agglutinin(WGA)-agarose and phenyl-Sepharose CL-4B. The partially purified[ ^3H]PGE_1-bound receptor was affinity-labeled with [ ^<14>C]5'-P-fluorosulfonylbenzoylguanosine and a protein with a molecular mass of 60 kDa was detected.Iloprost, a stable prostacyclin analogue, transiently stimulated adenylate cyclase activity. floprost also induced the translocation of alpha subunits(42- and 45-kDa)of stimulatory guanine nucleotide-binding proteins(Gsalpha)from the membrane to the cytosol. These results taken together demonstrate the the desensitization of prostaglandin receptors, 'are caused by distinct mechanisms between those of prostaglandin E_1 and prostacyclin.