Department of Physiology Biophysics and Neurosciences, and Department of Molecular Biomedicine, Center for Research and Advanced Studies, CINVESTAV-IPN, Mexico DF 07300, Mexico.
Mol Biol Cell. 2010 Jul 1;21(13):2217-25. doi: 10.1091/mbc.e10-01-0081. Epub 2010 May 5.
The very existence of higher metazoans depends on the vectorial transport of substances across epithelia. A crucial element of this transport is the membrane enzyme Na(+),K(+)-ATPase. Not only is this enzyme distributed in a polarized manner in a restricted domain of the plasma membrane but also it creates the ionic gradients that drive the net movement of glucose, amino acids, and ions across the entire epithelium. In a previous work, we have shown that Na(+),K(+)-ATPase polarity depends on interactions between the beta subunits of Na(+),K(+)-ATPases located on neighboring cells and that these interactions anchor the entire enzyme at the borders of the intercellular space. In the present study, we used fluorescence resonance energy transfer and coprecipitation methods to demonstrate that these beta subunits have sufficient proximity and affinity to permit a direct interaction, without requiring any additional extracellular molecules to span the distance.
高等后生动物的存在依赖于物质通过上皮的向量运输。这种运输的一个关键元素是膜酶 Na(+)，K(+) - ATP 酶。这种酶不仅以极化的方式分布在质膜的一个受限区域，而且还产生驱动葡萄糖、氨基酸和离子穿过整个上皮的净运动的离子梯度。在以前的工作中，我们已经表明，Na(+)，K(+) - ATP 酶的极性取决于位于相邻细胞上的 Na(+)，K(+) - ATP 酶的β亚基之间的相互作用，并且这些相互作用将整个酶锚定在细胞间隙的边界处。在本研究中，我们使用荧光共振能量转移和共沉淀方法证明这些β亚基具有足够的接近度和亲和力以允许直接相互作用，而不需要任何额外的细胞外分子来跨越距离。
