Department of Physiology Biophysics and Neurosciences, Center for Research and Advanced Studies, CINVESTAV-IPN, Mexico City 07360, Mexico.
Laboratorio de Diseño y Desarrollo de Nuevos Fármacos e Innovación Biotécnológica, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, Mexico City 11340, Mexico.
Int J Mol Sci. 2019 Sep 13;20(18):4538. doi: 10.3390/ijms20184538.
The Na, K-ATPase transports Na and K across the membrane of all animal cells. In addition to its ion transporting function, the Na, K-ATPase acts as a homotypic epithelial cell adhesion molecule via its β subunit. The extracellular region of the Na, K-ATPase β subunit includes a single globular immunoglobulin-like domain. We performed Molecular Dynamics simulations of the ectodomain of the β subunit and a refined protein-protein docking prediction. Our results show that the β subunit Ig-like domain maintains an independent structure and dimerizes in an antiparallel fashion. Analysis of the putative interface identified segment Lys221-Tyr229. We generated triple mutations on YFP-β subunit fusion proteins to assess the contribution of these residues. CHO fibroblasts transfected with mutant β subunits showed a significantly decreased cell-cell adhesion. Association of β subunits in vitro was also reduced, as determined by pull-down assays. Altogether, we conclude that two Na, K-ATPase molecules recognize each other by a large interface spanning residues 221-229 and 198-207 on their β subunits.
钠钾 ATP 酶在所有动物细胞的膜上转运钠和钾。除了其离子转运功能外，钠钾 ATP 酶通过其β亚基作为同质上皮细胞黏附分子发挥作用。钠钾 ATP 酶β亚基的细胞外区域包括一个单一的球形免疫球蛋白样结构域。我们对β亚基的胞外结构域进行了分子动力学模拟和经过优化的蛋白-蛋白对接预测。我们的结果表明，β亚基 Ig 样结构域保持独立的结构，并以反平行的方式二聚化。对接界面分析确定了关键残基 Lys221-Tyr229。我们在 YFP-β 亚基融合蛋白上生成了三个突变，以评估这些残基的贡献。转染了突变β亚基的 CHO 成纤维细胞显示出细胞间黏附显著降低。通过下拉实验也确定了体外β亚基的相互作用减少。总之，我们得出结论，两个钠钾 ATP 酶分子通过其β亚基上的残基 221-229 和 198-207 之间的大界面相互识别。
