Usery Rebecca D, Enoki Thais A, Wickramasinghe Sanjula P, Weiner Michael D, Tsai Wen-Chyan, Kim Mary B, Wang Shu, Torng Thomas L, Ackerman David G, Heberle Frederick A, Katsaras John, Feigenson Gerald W
Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York.
Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York; Department of Biochemistry and Biophysics at the University of Pennsylvania, Philadelphia, Pennsylvania.
Biophys J. 2017 Apr 11;112(7):1431-1443. doi: 10.1016/j.bpj.2017.02.033.
To better understand animal cell plasma membranes, we studied simplified models, namely four-component lipid bilayer mixtures. Here we describe the domain size transition in the region of coexisting liquid-disordered (Ld) + liquid-ordered (Lo) phases. This transition occurs abruptly in composition space with domains increasing in size by two orders of magnitude, from tens of nanometers to microns. We measured the line tension between coexisting Ld and Lo domains close to the domain size transition for a variety of lipid mixtures, finding that in every case the transition occurs at a line tension of ∼0.3 pN. A computational model incorporating line tension and dipole repulsion indicated that even small changes in line tension can result in domains growing in size by several orders of magnitude, consistent with experimental observations. We find that other properties of the coexisting Ld and Lo phases do not change significantly in the vicinity of the abrupt domain size transition.
为了更好地理解动物细胞质膜，我们研究了简化模型，即四组分脂质双层混合物。在此，我们描述了共存的液相无序（Ld）+液相有序（Lo）相区域中的畴尺寸转变。这种转变在成分空间中突然发生，畴尺寸增大两个数量级，从几十纳米增加到微米。我们测量了多种脂质混合物在接近畴尺寸转变时共存的Ld和Lo畴之间的线张力，发现在每种情况下，转变都发生在线张力约为0.3 pN时。一个包含线张力和偶极排斥的计算模型表明，即使线张力的微小变化也会导致畴尺寸增大几个数量级，这与实验观察结果一致。我们发现，共存的Ld和Lo相的其他性质在畴尺寸突然转变附近没有显著变化。
