Parathyroid hormone receptor in human placental syncytiotrophoblast brush border and basal plasma membranes

摘要: The syncytiotrophoblast of the placenta is site exchange nutrients and minerals between mother fetus. We have recently demonstrated that PTH influences, in vitro, phosphate transport through brush border membranes (BBM) increases cAMP accumulation placental tissue. To demonstrate binding cytoplasmic membrane, we purified two polar membranes: first located on apical side, BBM, second, fetal basal plasma membrane (BPM). BBM were enriched 24-fold alkaline phosphatase (marker for BBM), BPM was 37-fold [3H] dihydroalprenolol BPM) compared to homogenate. Both contain sites (maximum = 0.550 +/- 0.032 0.298 0.065 pmol/mg protein BPM, respectively) with similar affinities (Kd 2.05 0.23 1.78 0.19 nM, 125I-[Nle8,Nle18,Tyr34] bovine (b) PTH-(1-34) amide. three preparations [bPTH-(1-34), its analog [Nle8,Nle18,Try34]bPTH-(1-34) amide, antagonist bPTH-(3-34)] equipotent both membranes. In contrast, human PTH-(1-84) more effective displacing radioligand BBM. Thyrocalcitonin insulin, non-PTH peptides, did not significantly displace BPM. Adenylate cyclase activity, exclusively stimulated by PTH. Since enzyme absent from it probable hormone this activates another system messengers.