Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, United States of America.
Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, United States of America.
Biochim Biophys Acta Biomembr. 2019 Feb 1;1861(2):478-485. doi: 10.1016/j.bbamem.2018.11.010. Epub 2018 Dec 5.
Chemically simplified lipid mixtures are used here as models of the cell plasma membrane exoplasmic leaflet. In such models, phase separation and morphology transitions controlled by line tension in the liquid-disordered (Ld) + liquid-ordered (Lo) coexistence regime have been described [1]. Here, we study two four-component lipid mixtures at different cholesterol fractions: brain sphingomyelin (BSM) or 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC)/1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/cholesterol (Chol). On giant unilamellar vesicles (GUVs) display a nanoscopic-to-macroscopic transition of Ld + Lo phase domains as POPC is replaced by DOPC, and this transition also depends on the cholesterol fraction. Line tension decreases with increasing cholesterol mole fractions in both lipid mixtures. For the ternary BSM/DOPC/Chol mixture, the published phase diagram [19] requires a modification to show that when cholesterol mole fraction is >~0.33, coexisting phase domains become nanoscopic.
这里使用化学简化的脂质混合物作为细胞质膜胞质小叶的模型。在这些模型中，已经描述了由线张力控制的在无序相 (Ld) + 有序相 (Lo) 共存区的相分离和形态转变[1]。在这里，我们研究了两种不同胆固醇分数的四组分脂质混合物：脑鞘磷脂 (BSM) 或 1,2-二硬脂酰基-sn-甘油-3-磷酸胆碱 (DSPC)/1,2-二油酰基-sn-甘油-3-磷酸胆碱 (DOPC)/1-棕榈酰基-2-油酰基-sn-甘油-3-磷酸胆碱 (POPC)/胆固醇 (Chol)。在巨大的单层囊泡 (GUV) 上，随着 POPC 被 DOPC 取代，Ld + Lo 相畴发生纳米级到宏观级的转变，这种转变也取决于胆固醇分数。在这两种脂质混合物中，线张力随胆固醇摩尔分数的增加而降低。对于三元 BSM/DOPC/Chol 混合物，需要对已发表的相图[19]进行修改，以表明当胆固醇摩尔分数>~0.33 时，共存相畴变得纳米级。
