Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305.
Department of Chemistry, Stanford University, Stanford, CA 94305.
Proc Natl Acad Sci U S A. 2024 Mar 5;121(10):e2319491121. doi: 10.1073/pnas.2319491121. Epub 2024 Mar 1.
Translocation of cytoplasmic molecules to the plasma membrane is commonplace in cell signaling. Membrane localization has been hypothesized to increase intermolecular association rates; however, it has also been argued that association should be faster in the cytosol because membrane diffusion is slow. Here, we directly compare an identical association reaction, the binding of complementary DNA strands, in solution and on supported membranes. The measured rate constants show that for a 10-µm-radius spherical cell, association is 22- to 33-fold faster at the membrane than in the cytoplasm. The kinetic advantage depends on cell size and is essentially negligible for typical ~1 µm prokaryotic cells. The rate enhancement is attributable to a combination of higher encounter rates in two dimensions and a higher reaction probability per encounter.
细胞质分子向质膜的转位在细胞信号中很常见。膜定位被假设可以增加分子间的缔合速率;然而，也有人认为由于膜扩散缓慢，在细胞质中缔合应该更快。在这里，我们直接比较了相同的缔合反应，即互补 DNA 链在溶液中和在支撑膜上的结合。测量的速率常数表明，对于半径为 10µm 的球形细胞，在膜上的缔合速度比在细胞质中快 22 到 33 倍。这种动力学优势取决于细胞的大小，对于典型的~1µm 原核细胞来说，可以忽略不计。这种速率增强归因于二维中更高的遭遇率和每一次遭遇更高的反应概率的组合。
