期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1979
卷号：76
期号：11
页码：5645-5649
DOI：10.1073/pnas.76.11.5645
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The technique of fluorescence recovery after photobleaching was used to investigate the lateral mobility of a fluorescein-labeled amphipathic apolipoprotein, ApoC-III, bound to multibilayers prepared from dipalmitoyl phosphatidylcholine, egg phosphatidylcholine, and a 1:1 (molar ratio) mixture of egg phosphatidylcholine and cholesterol. In dipalmitoyl phosphatidylcholine bilayers the lateral diffusion coefficient (D) for the protein is about 2 x 10-9 cm2 sec-1 at 20{degrees}C and about 9 x 10-8 cm2 sec-1 at 45{degrees}C. Plots of D versus temperature in this system show a transition between about 30 and 35{degrees}C. Arrhenius activation energies for the diffusion in this case between 15 and 30{degrees}C and between 35 and 45{degrees}C are 28.5 and 7.0 kcal mol-1, respectively (1 calorie = 4.18 joules). In egg phosphatidylcholine bilayers, D is about 3 x 10-8 cm2 sec-1 at 20{degrees}C and the Arrhenius activation energy for diffusion is 8.1 kcal mol-1 between 15 and 35{degrees}C in this system. In bilayers prepared from an equimolar mixture of egg phosphatidylcholine and cholesterol D at 20{degrees}C is about 1.4 x 10-9 cm2 sec-1 and the Arrhenius activation energy for the diffusion of the protein in this system between 15 and 35{degrees}C is 15.1 kcal mol-1. Light-scattering and fluorescence-polarization results indicate that binding of this protein does not affect the gel-to-liquid crystalline phase transition of bilayer membranes but does mediate a major, reversible aggregation of the vesicles at about 33{degrees}C. These results lend support to the view that ApoC-III resides in the head-group region of the bilayer and suggest that its lateral diffusion coefficient represents an upper bound for integral membrane proteins.
关键词：membrane lateral diffusion ; fluorescence recovery after photobleaching
