Frolov V A J, Chizmadzhev Y A, Cohen F S, Zimmerberg J
Frumkin Institute of Electrochemistry, Russian Academy of Sciences, Moscow, Russia.
Biophys J. 2006 Jul 1;91(1):189-205. doi: 10.1529/biophysj.105.068502. Epub 2006 Apr 14.
We quantitatively describe the creation and evolution of phase-separated domains in a multicomponent lipid bilayer membrane. The early stages, termed the nucleation stage and the independent growth stage, are extremely rapid (characteristic times are submillisecond and millisecond, respectively) and the system consists of nanodomains of average radius approximately 5-50 nm. Next, mobility of domains becomes consequential; domain merger and fission become the dominant mechanisms of matter exchange, and line tension gamma is the main determinant of the domain size distribution at any point in time. For sufficiently small gamma, the decrease in the entropy term that results from domain merger is larger than the decrease in boundary energy, and only nanodomains are present. For large gamma, the decrease in boundary energy dominates the unfavorable entropy of merger, and merger leads to rapid enlargement of nanodomains to radii of micrometer scale. At intermediate line tensions and within finite times, nanodomains can remain dispersed and coexist with a new global phase. The theoretical critical value of line tension needed to rapidly form large rafts is in accord with the experimental estimate from the curvatures of budding domains in giant unilamellar vesicles.
我们定量描述了多组分脂质双层膜中相分离域的形成和演化。早期阶段，称为成核阶段和独立生长阶段，极其迅速（特征时间分别为亚毫秒和毫秒），系统由平均半径约为5 - 50 nm的纳米域组成。接下来，域的流动性变得至关重要；域的合并和裂变成为物质交换的主要机制，线张力γ是任何时刻域尺寸分布的主要决定因素。对于足够小的γ，域合并导致的熵项减少大于边界能的减少，此时仅存在纳米域。对于大的γ，边界能的减少主导了不利的合并熵，合并导致纳米域迅速扩大到微米尺度的半径。在中等线张力和有限时间内，纳米域可以保持分散并与新的全局相共存。快速形成大筏所需的线张力理论临界值与来自巨型单层囊泡中出芽域曲率的实验估计值一致。
