APICAL AND BASOLATERAL PARATHYROID-HORMONE RECEPTORS IN RAT RENAL CORTICAL MEMBRANES
APICAL AND BASOLATERAL PARATHYROID-HORMONE RECEPTORS IN RAT RENAL CORTICAL MEMBRANES
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DOI：
10.1210/en.134.3.1173
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发表时间：
1994-03-01
期刊：
影响因子：
4.8
通讯作者：
FISCHER, JA
中科院分区：
文献类型：
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作者：
KAUFMANN, M;MUFF, R;FISCHER, JA
用自由流动电泳法分离大鼠肾皮质细胞刷状缘(BBM)和基侧膜(BLM)，发现BBM特异的亮氨酸氨基肽酶和BLM的Na+/K+-ATPase有两个明显的峰。甲状旁腺激素/甲状旁腺激素相关蛋白(PTHrP)受体定位于BBM和BLM。125 Pm[I-125]鸡[Tyr(36)]-PTHrP-(1-36)酰胺[chPTHrP-(1-36)]与自由流动电泳法分离的膜组分的特异性结合与亮氨酸氨基肽酶和Na+/K+-ATPase图谱重叠。与混合BBM的结合率为BLM的53+/-5%(平均+/-SEM)(P<；0.01)。在BBM和BLM中，0.4-0.9 nM chPTHrP-(1-36)和0.2-0.6 nM大鼠PTH-(1-34)对结合的抑制作用达到一半最大。鸟苷5‘-0-(3-硫代三磷酸)(GTP-γS；100mM)可将chPTHrP-(1-36)结合降低至对照的50%，480 nM和8 nM GTP-S对BBM和BLM中chPTHrP-(1-36)结合的抑制作用分别为对照组的一半。甲状旁腺素/甲状旁腺素受体与N-羟基琥珀酰亚胺基-4-叠氮苯甲酸酯修饰的[I-125]chPTHrP-(1-36)在BBM和BLM中显示出无法区分的83和73千道尔顿的双重体。CHPTHrP-(1-36)和GTP-γS分别刺激BLm和BBM的腺酰环酶活性6倍和10倍。综上所述，甲状旁腺激素受体在基底外侧膜和刷状缘膜上均可识别。BBM对G蛋白的不同受体偶联和对cAMP的最小刺激为BBM和BLM的PTH/PTHrP受体亚型和/或不同受体后激活提供了证据。
Brush border (BBM) and basolateral membranes (BLM) of rat renal cortical cells separated by free flow electrophoresis revealed two distinct peaks of BBM-specific leucine aminopeptidase and Na+/K+-ATPase for BLM. PTH/PTH-related protein (PTHrP) receptors were identified in BBM and BLM. Specific binding of 125 pM [I-125]chicken [Tyr(36)]-PTHrP-(1-36)amide [chPTHrP-(1-36)] to individual fractions of membranes separated by free flow electrophoresis overlapped with the leucine aminopeptidase and Na+/K+-ATPase profiles. Binding to pooled BBM was 53 +/- 5% (mean +/- SEM) of that to BLM (P < 0.01). In BBM and BLM, half-maximal inhibition of binding was obtained with 0.4-0.9 nM chPTHrP-(1-36) and 0.2-0.6 nM rat PTH-(1-34). Guanosine 5'-0-(3-thiotriphosphate) (GTP gamma S; 100 mu M) lowered chPTHrP-(1-36) binding to 50% of control levels, and half-maximal inhibition of binding was obtained with 480 and 8 nM GTP gamma S in BBM and BLM, respectively. Cross-linking of the PTH/PTHrP receptors with [I-125]chPTHrP-(1-36) modified with N-hydroxysuccinimidyl-4-azidobenzoate revealed indistinguishable doublets of 83 and 73 kilodaltons in both BBM and BLM. Adenylyl cyclase was stimulated 6- and 10-fold by chPTHrP-(1-36) and GTP gamma S, respectively, in BLM and 1.3- and 1.9-fold in BBM. In conclusion, PTH receptors were recognized in both the basolateral and brush border membranes. Different receptor coupling to G-proteins and minimal cAMP stimulation in BBM provide evidence for PTH/PTHrP receptor isotypes and/or different postreceptor activation in BBM and BLM.