THE EXTRACELLULAR AMINO-TERMINAL REGION OF THE PARATHYROID-HORMONE (PTH)/PTH-RELATED PEPTIDE RECEPTOR DETERMINES THE BINDING-AFFINITY FOR CARBOXYL-TERMINAL FRAGMENTS OF PTH-(1-34)
THE EXTRACELLULAR AMINO-TERMINAL REGION OF THE PARATHYROID-HORMONE (PTH)/PTH-RELATED PEPTIDE RECEPTOR DETERMINES THE BINDING-AFFINITY FOR CARBOXYL-TERMINAL FRAGMENTS OF PTH-(1-34)
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DOI：
10.1210/en.134.2.879
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发表时间：
1994-02-01
期刊：
影响因子：
4.8
通讯作者：
GARDELLA, TJ
中科院分区：
文献类型：
--
作者：
JUPPNER, H;SCHIPANI, E;GARDELLA, TJ
当在COS-7细胞中瞬时表达时，重组人PTH/PTH相关肽（PTHrP）受体结合[Nle（8，18），Tyr（34）]牛PTH-（7 -34）酰胺[PTH-（7 -34）]，人PTH-（10 -34）酰胺[PTH-（10-34）]，和牛PTH-（15-34）酰胺[PTH-（15-34）]，其亲和力比大鼠受体同系物高至少50倍。为了定位决定PTH-（1 - 34）羧基末端片段结合特异性的PTH/PTHrP受体区域，我们构建了大鼠/人嵌合PTH/PTHrP受体。它们以正常亲和力结合PTH-（1-34），因此必须具有类似于天然受体的整体构象。具有人PTH/ PTHrP受体的氨基末端胞外结构域的嵌合体对PTH-（7-34）、PTH-（10-34）和PTH-（15-34）具有比其中氨基末端区域来自大鼠PTH/PTHrP受体的相互受体构建体高得多的结合亲和力。负鼠PTH/PTHrP受体同系物也以比大鼠受体更高的亲和力结合PTH-（7-34），并且大鼠/负鼠嵌合体的研究证实了氨基末端胞外结构域在确定PTH-（7-34）结合特异性中的重要性。突变的大鼠和人PTH/PTHrP受体（其中胞外区的残基61-105或大部分胞内尾缺失）具有与任一野生型受体无区别的PTH-（7-34）结合特性。这些发现表明PTH/PTHrP受体的氨基末端胞外区含有在很大程度上决定氨基-（7-34）结合亲和力的结构域。末端截短的PTH类似物。因此，该区域可能构成配体-受体相互作用的位点。
The recombinant human PTH/PTH-related peptide (PTHrP) receptor, when transiently expressed in COS-7 cells, binds [Nle(8,18),Tyr(34)] bovine PTH-(7-34)amide [PTH-(7-34)], human PTH-(10-34)amide [PTH-(10-34)], and bovine PTH-(15-34)amide [PTH-(15-34)] with at least 50-fold higher affinity than does the rat receptor homolog. In contrast, PTH-(1-34) binding affinities are similar for both receptor homologs.To map those areas of the PTH/PTHrP receptors that determine the binding specificity for carboxyl-terminal fragments of PTH-(1-34), we constructed chimeric rat/human PTH/PTHrP receptors. These bound PTH-(1-34) with normal affinity and, therefore, must have an overall conformation that resembles that of native receptors. Chimeras with the amino-terminal extracellular domain of the human PTH/ PTHrP receptor have a considerably higher binding affinity for PTH-(7-34), PTH-(10-34), and PTH-(15-34) than do the reciprocal receptor constructs in which the amino-terminal region is from the rat PTH/PTHrP receptor. The opossum PTH/PTHrP receptor homolog also binds PTH-(7-34) with higher affinity than the rat receptor, and studies of rat/opossum chimeras confirm the importance of the amino-terminal extracellular domain in determining the PTH-(7-34) binding specificity. Mutant rat and human PTH/PTHrP receptors in which either residues 61-105 of the extracellular region or most of the intracellular tail were deleted have PTH-(7-34) binding characteristics indistinguishable from those of either wild-type receptor.These findings indicate that the amino-terminal extracellular region of the PTH/PTHrP receptor contains a domain(s) that largely determines the binding affinity of amino-terminally truncated PTH analogs. This region, therefore, is likely to constitute a site for ligand-receptor interaction.