Structural requirements for ligand binding by a probable plant vacuolar sorting receptor
Structural requirements for ligand binding by a probable plant vacuolar sorting receptor
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DOI：
10.1105/tpc.12.4.493
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发表时间：
2000-04-01
期刊：
影响因子：
11.6
通讯作者：
Rogers, JC
中科院分区：
文献类型：
--
作者：
Cao, XF;Rogers, SW;Rogers, JC
分选受体如何识别多肽配体上的氨基酸决定因子，并对配体结合或释放的pH变化做出反应尚不清楚。植物液泡分选受体BP-80与中心asn - pro - il - arg （NPIR）基序结合多肽配体，tBP-80是一种缺乏跨膜和细胞质序列的可溶性受体形式，与肽SSSFADSNPIRPVTDRAASTYC作为一个单体结合，其特异性与BP-80难以区分。tap-so包含一个与RMR蛋白腔域同源的n端区域、一个独特的中心区域和三个c端表皮生长因子（EGF）重复序列。通过蛋白酶消化纯化的分泌tBP-80，以及与缺乏EGF重复序列的分泌蛋白的配体结合研究，我们定义了三个蛋白酶抗性结构域：一个与中心结构域相连的n端/RMR同源结构域，它们共同决定了npir特异性配体结合位点，以及一个c端EGF重复结构域，它改变了其他两个结构域的构象，以增强配体结合。这些结果表明，两个tBP-80结合位点识别两个独立的配体决定因子：一个由中心结构域- egf重复结构域定义的非NPIR位点，以及一个由n端/RMR同源结构域和中心结构域相互作用贡献的NPIR特异性位点。
How sorting receptors recognize amino acid determinants on polypeptide ligands and respond to pH changes for ligand binding or release is unknown. The plant vacuolar sorting receptor BP-80 binds polypeptide ligands with a central Asn-Pro-Ile-Arg (NPIR) motif, tBP-80, a soluble form of the receptor lacking transmembrane and cytoplasmic sequences, binds the peptide SSSFADSNPIRPVTDRAASTYC as a monomer with a specificity indistinguishable from that of BP-80. tap-so contains an N-terminal region homologous to ReMembR-H2 (RMR) protein lumenal domains, a unique central region, and three C-terminal epidermal growth factor (EGF) repeats. By protease digestion of purified secreted tBP-80, and from ligand binding studies with a secreted protein lacking the EGF repeats, we defined three protease-resistant structural domains: an N-terminal/RMR homology domain connected to a central domain, which together determine the NPIR-specific ligand binding site, and a C-terminal EGF repeat domain that alters the conformation of the other two domains to enhance ligand binding. A fragment representing the central domain plus the C-terminal domain could bind ligand but was not specific for NPIR, These results indicate that two tBP-80 binding sites recognize two separate ligand determinants: a non-NPIR site defined by the central domain-EGF repeat domain structure and an NPIR-specific site contributed by the interaction of the N-terminal/RMR homology domain and the central domain.