Stuschke M, Bojar H
Biochim Biophys Acta. 1985 Jun 30;845(3):436-44. doi: 10.1016/0167-4889(85)90209-5.
The effects of insulin (10(-10)-10(-8) mol/l) on lateral diffusion of three fluorescent lipid probes, 1-acyl-2-(N-4-nitrobenzo-2-oxa-1,3-diazole)aminocaproyl phosphatidylcholine (NBD-PC), 5-(N-hexadecanoyl)aminofluorescein (F-C16), 5-(N-dodecanoyl)aminofluorescein (F-C12), and of fluorescein isothiocyanate-labeled proteins in the plasma membrane of intact rat hepatocytes were studied by the technique of fluorescence recovery after photobleaching. The absolute lateral diffusion coefficients of the lipid analogues NBD-PC, F-C16 and F-C12 at 21 degrees C were 2.5 X 10(-9) cm2/s, 5.4 X 10(-9) cm2/s and 19 X 10(-9) cm2/s, respectively. The diffusion coefficient mean of proteins labeled with fluorescein isothiocyanate was 6.4 X 10(-10) cm2/s. Insulin at 10(-9) and 10(-8) mol/l reduced the lateral diffusion coefficient for F-C12- and F-C16-labeled cells by 20% and for NBD-PC-labeled cells by 30% (P less than 0.025). The insulin effect was specific as tested by cell incubation with proinsulin and desoctapeptide insulin (10(-8) mol/l) and was detectable after 7 min of insulin preincubation. In contrast to lateral diffusion of lipid probes, lateral mobility of unselected membrane proteins was not altered by insulin. The observed modulation of lipid dynamics in the plasma membrane of intact hepatocytes, by which a variety of membrane functions can be influenced, may be an important step in the mechanism of insulin action.
采用光漂白后荧光恢复技术，研究了胰岛素（10⁻¹⁰ - 10⁻⁸mol/L）对完整大鼠肝细胞质膜中三种荧光脂质探针[1-酰基-2-（N-4-硝基苯并-2-恶唑-1,3-二氮杂环戊二烯）氨基己酰磷脂酰胆碱（NBD-PC）、5-（N-十六烷酰基）氨基荧光素（F-C16）、5-（N-十二烷酰基）氨基荧光素（F-C12）]以及异硫氰酸荧光素标记蛋白侧向扩散的影响。在21℃时，脂质类似物NBD-PC、F-C16和F-C12的绝对侧向扩散系数分别为2.5×10⁻⁹cm²/s、5.4×10⁻⁹cm²/s和19×10⁻⁹cm²/s。异硫氰酸荧光素标记蛋白的扩散系数平均值为6.4×10⁻¹⁰cm²/s。10⁻⁹和10⁻⁸mol/L的胰岛素使F-C12和F-C16标记细胞的侧向扩散系数降低20%，使NBD-PC标记细胞的侧向扩散系数降低30%（P＜0.025）。用胰岛素原和去八肽胰岛素（10⁻⁸mol/L）孵育细胞进行测试，结果表明胰岛素的作用具有特异性，且在胰岛素预孵育7分钟后即可检测到。与脂质探针的侧向扩散不同，胰岛素并未改变未选择的膜蛋白的侧向流动性。完整肝细胞质膜中脂质动力学的这种变化可影响多种膜功能，这可能是胰岛素作用机制中的一个重要步骤。
