Mechanism for binding site diversity on ankyrin - Comparison of binding sites on ankyrin for neurofascin and the Cl-/HCO3- anion exchanger
Mechanism for binding site diversity on ankyrin - Comparison of binding sites on ankyrin for neurofascin and the Cl-/HCO3- anion exchanger
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DOI：
10.1074/jbc.270.52.31298
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发表时间：
1995-12-29
影响因子：
4.8
通讯作者：
Bennett, V
中科院分区：
文献类型：
--
作者：
Michaely, P;Bennett, V
锚蛋白是血影蛋白结合蛋白家族，其与至少七种不同的膜蛋白（包括离子转运蛋白和细胞粘附分子）缔合。锚蛋白的膜结合结构域由24个ANK重复序列的串联阵列组成，这些ANK重复序列被组织成4个6重复折叠结构域。ANK重复序列的串联阵列已经被提出来介导多种蛋白质中的蛋白质相互作用，包括参与转录和细胞周期调节的因子。本报告提供了几个新的见解ANK重复序列的多功能性的蛋白质识别，使用神经成束蛋白和Cl-/HCO 3-阴离子交换剂作为模型配体和锚蛋白，作为原型锚蛋白。来自该锚蛋白的ANK重复结构域的不同组合形成两个不同的、高亲和力的神经成束蛋白结合位点，一个位点需要重复结构域3和4。另一个位点涉及重复结构域2和3，尽管结构域2单独具有显著的活性。这些位点似乎是独立的，Kd值为3和14 nM。分别Cl-/HCO 3-阴离子交换剂和神经成束蛋白都可以同时与重复结构域3和4相互作用，因为神经成束蛋白不能取代阴离子交换剂胞质结构域与结构域3和4的结合，尽管具有3-5倍高的亲和力。这些结果证明了锚蛋白上结合位点的两个水平的多样性：一种由ANK重复结构域的不同组合产生，另一种由相同重复结构域组合内的不同de决定簇产生，这种多样性的一个结果是锚蛋白可以通过ANK介导的相互作用容纳两个神经成束蛋白分子以及阴离子交换剂锚蛋白同时与多种类型的膜蛋白结合的能力是一个意想不到的发现，其暗示了整合膜蛋白组装成质膜的专门区域。
Ankyrins are a family of spectrin-binding proteins that associate with at least seven distinct membrane proteins, including ion transporters and cell adhesion molecules. The membrane-binding domain of ankyrin is comprised of a tandem array of 24 ANK repeats organized into four 6-repeat folding domains. Tandem arrays of ANK repeats have been proposed to mediate protein interactions in a variety of proteins including factors involved in the regulation of transcription and the cell cycle, This report provides several new insights into the versatility of ANK repeats of ankyrin in protein recognition, using neurofascin and the Cl-/HCO3- anion exchanger as model ligands and ankyrin, as the prototypic ankyrin. Different combinations of ANK repeat domains from this ankyrin form two distinct, high affinity binding sites for neurofascin, One site requires both repeat domains 3 and 4. The other site involves both repeat domains 2 and 3, although domain 2 has significant activity alone. The sites appear to be independent with K-d values of 3 and 14 nM. respectively. Both the Cl-/HCO3- anion exchanger and neurofascin can interact simultaneously with repeat domains 3 and 4, because neurofascin is unable to displace binding of the anion exchanger cytoplasmic domain to domains 3 and 4, despite having a 3-5-fold higher affinity, These results demonstrate two levels of diversity in the binding sites on ankyrin: one resulting from different combinations of ANK repeat domains and another from different de determinants within the same combination of repeat domains, One consequence of this diversity is that ankyrin can accommodate two neurofascin molecules as well as the anion exchanger through interactions mediated by ANK repeats, The ability of ankyrin to simultaneously associate with multiple types of membrane proteins is an unanticipated finding with implications for the assembly of integral membrane proteins into specialized regions of the plasma membrane.