Martin C E, Hiramitsu K, Kitajima Y, Nozawa Y, Skriver L, Thompson G A
Biochemistry. 1976 Nov 30;15(24):5218-27. doi: 10.1021/bi00669a004.
This is a study of the molecular mechanisms employed by Tetrahymena pyriformis to change the lipid composition and thereby the fluidity of its various membranes during temperature acclimation. By quantitatively measuring the intramembrane particle aggregation using freeze-fracture electron microscopy, membrane physical properties in 39.5 degrees C grown cells shifted to 15 degrees C were found to be correlated with the degree of phospholipid fatty acid desaturation. Alteration of the phospholipid polar head group distribution from that of 39.5 degrees C-grown cells to the significantly different pattern of 15 degrees C grown cells appeared not to be of critical importance in the acclimation process. Changes in fatty acid desaturation during acclimation from high to low temperatures and vice versa were analyzed using normal cells and cells fed large amounts of polyunsaturated fatty acids. Fatty acid desaturase activity corresponded to the degree of membrane fluidity but not to the cell temperature. All evidence was compatible with the hypothesis that membrane fluidity is self-regulating, with the action of fatty acid desaturases being modulated by the physical state of their membrane environment.
这是一项关于梨形四膜虫在温度适应过程中改变脂质组成从而改变其各种膜流动性所采用分子机制的研究。通过使用冷冻断裂电子显微镜定量测量膜内颗粒聚集，发现从39.5℃生长的细胞转移到15℃后，膜的物理性质与磷脂脂肪酸去饱和程度相关。在适应过程中，磷脂极性头部基团分布从39.5℃生长细胞的模式转变为15℃生长细胞显著不同的模式，这似乎并非至关重要。使用正常细胞和喂食大量多不饱和脂肪酸的细胞，分析了从高温到低温以及反之从低温到高温适应过程中脂肪酸去饱和的变化。脂肪酸去饱和酶活性与膜流动性程度相对应，而与细胞温度无关。所有证据都与膜流动性是自我调节的这一假设相符，脂肪酸去饱和酶的作用受其膜环境物理状态的调节。
