Regulation of cystic fibrosis transmembrane conductance regulator single-channel gating by bivalent PDZ-domain-mediated interaction
Regulation of cystic fibrosis transmembrane conductance regulator single-channel gating by bivalent PDZ-domain-mediated interaction
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DOI：
10.1073/pnas.031538898
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发表时间：
2001-01-30
影响因子：
11.1
通讯作者：
Foskett, JK
中科院分区：
文献类型：
--
作者：
Raghuram, V;Mak, DOD;Foskett, JK
囊性纤维化跨膜传导调节因子（CFTR）是一种cAMP依赖性蛋白激酶和ATP调节的氯离子通道，其活性决定了各种上皮组织中电解质和液体转运的速率。在这里，我们描述了一种调节CFTR通道活性的机制，该机制由保守蛋白质相互作用模块家族PDZ结构域介导。Na+/H+交换调节因子（NHERF）通过其两个PDZ之一结合CFTR的胞质尾部（PDZ 1和PDZ 2）结构域，含有两个PDZ结构域的NHERF重组片段（PDZ 1 -2）增加了开放概率（P-o）这两个PDZ结构域都是这种功能效应所需的，因为在任一结构域中含有突变的肽不能增加通道P-o。二价PDZ 1 -2结构域的调节的浓度依赖性是双相的，即，在较低浓度下激活，在较高浓度下抑制。此外，PDZ结构域单独或一起对P-o没有影响，但任一结构域都可以竞争性地抑制PDZ 1 -2介导的CFTR刺激。我们的结果支持了一种分子模型，其中二价NHERF PDZ结构域通过交联单个二聚体CFTR通道中的C末端尾部来调节通道门控，并且这种调节的幅度与这些相互作用的化学计量学相关联。
The cystic fibrosis transmembrane conductance regulator (CFTR) is a cAMP-dependent protein kinase- and ATP-regulated chloride channel, the activity of which determines the rate of electrolyte and fluid transport in a variety of epithelial tissues. Here we describe a mechanism that regulates CFTR channel activity, which is mediated by PDZ domains, a family of conserved protein-interaction modules, The Na+/H+ exchanger regulatory factor (NHERF) binds to the cytoplasmic tail of CFTR through either of its two PDZ (PDZ1 and PDZ2) domains, A recombinant fragment of NHERF (PDZ1-2) containing the two PDZ domains increases the open probability (P-o) of single CFTR channels in excised membrane patches from a lung submucosal gland cell line, Both PDZ domains are required for this functional effect, because peptides containing mutations in either domain are unable to increase channel P-o. The concentration dependence of the regulation by the bivalent PDZ1-2 domain is biphasic, i.e., activating at lower concentrations and inhibiting at higher concentrations. Furthermore, either PDZ domain alone or together is without effect on P-o, but either domain can competitively inhibit the PDZ1-2-mediated stimulation of CFTR, Our results support a molecular model in which bivalent NHERF PDZ domains regulate channel gating by crosslinking the C-terminal tails in a single dimeric CFTR channel, and the magnitude of this regulation is coupled to the stoichiometry of these interactions.