Tittle Rachel K, Power Jamila M, Hume Richard I
Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109-1048, USA.
J Biol Chem. 2007 Jul 6;282(27):19526-33. doi: 10.1074/jbc.M701604200. Epub 2007 May 21.
The response of P2X(2) receptors to submaximal concentrations of ATP is potentiated by low levels of extracellular zinc. Histidines 120 and 213 have previously been shown to be essential in binding zinc across an intersubunit binding site. We tested the flexibility of the zinc-binding site by making mutations that had the effect of shifting the two essential histidines up to 13 residues upstream or downstream from their original positions and then testing the ability of the mutated receptors to respond to zinc. Using this method, we were able to explore potential orientations of the two regions relative to one another. Our data are consistent with a moderately flexible zinc-binding site and inconsistent with parallel and anti-parallel orientations of the regions surrounding histidines 120 and 213.
细胞外低水平锌可增强P2X(2)受体对亚最大浓度ATP的反应。先前已证明，组氨酸120和213对于通过亚基间结合位点结合锌至关重要。我们通过进行突变来测试锌结合位点的灵活性，这些突变可使两个必需的组氨酸从其原始位置向上游或下游移动多达13个残基，然后测试突变受体对锌的反应能力。使用这种方法，我们能够探索这两个区域相对于彼此的潜在取向。我们的数据与适度灵活的锌结合位点一致，与组氨酸120和213周围区域的平行和反平行取向不一致。
