DIFFERENTIAL MODULATION OF HUMAN SMALL INTESTINAL BRUSH-BORDER MEMBRANE HEMILEAFLET FLUIDITY AFFECTS LEUCINE AMINOPEPTIDASE ACTIVITY AND TRANSPORT OF D-GLUCOSE AND L-GLUTAMATE
DIFFERENTIAL MODULATION OF HUMAN SMALL INTESTINAL BRUSH-BORDER MEMBRANE HEMILEAFLET FLUIDITY AFFECTS LEUCINE AMINOPEPTIDASE ACTIVITY AND TRANSPORT OF D-GLUCOSE AND L-GLUTAMATE
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DOI：
10.1016/0003-9861(91)90305-3
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发表时间：
1991-02-01
影响因子：
3.9
通讯作者：
BRASITUS, TA
中科院分区：
文献类型：
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作者：
DUDEJA, PK;HARIG, JM;BRASITUS, TA
利用脂溶荧光团1，6-二苯基-1，3，5-己三烯，采用三硝基苯基选择性猝灭、稳态荧光偏振和差示偏振相荧光技术，研究了人近端小肠刷缘膜囊外(外)和细胞面(内)膜的流动性。通过氨基磷脂的三硝基苯基化和磷脂酶A2的处理，分析了半叶鱼磷脂组成的差异。这些研究的结果表明，这些膜的内叶比其外叶的流体更少。磷脂酰丝氨酸主要分布于内半叶，而磷脂酰乙醇胺和磷脂酰胆碱在该膜内半叶之间分布较为对称。此外，在体外加入2-[(2-methoxyethoxy)ethyl]-cis-8-(2-octylcyclopropyl)octanoate(终浓度，7.5mM)时，优先使细胞表面小叶流动，同时增加这些膜囊对Na+-梯度依赖的葡萄糖的摄取，但降低对Na+，K+-谷氨酸的摄取；在体外加入苯甲醇(终浓度，25 mM)时，优先使细胞表面小叶流动，降低这些制剂中亮氨酸氨基肽酶的活性。因此，这些结果表明，人小肠刷状缘膜的半叶具有不同的磷脂组成和流动性。此外，表面或细胞表面小叶流动性的改变以一种不同的方式调节蛋白质介导的活动。
The fluidity of the exofacial (outer) and cytofacial (inner) leaflets of human proximal small intestinal brush-border membrane vesicles was studied by selective quenching by trinitrophenyl groups, steady-state fluorescence polarization, and differential polarized phase fluorometry techniques, utilizing the lipid soluble fluorophore 1,6-diphenyl-1,3,5-hexatriene. Differences in the hemileaflet's phospholipid composition were also analyzed by trinitrophenylation of aminophospholipids and phospholipase A2treatment of these preparations. The results of these studies demonstrated that the inner leaflet of these membranes was less fluid than its outer counterpart. Phosphatidylserine was located mainly in the inner hemileaflet, whereas phosphatidylethanolamine and phosphatidylcholine were more symmetrically distributed between the hemileaflets of this membrane. Moreover,in vitroaddition of 2-[(2-methoxyethoxy)ethyl]-cis-8-(2-octylcyclopropyl)octanoate (final concentration, 7.5 μm) preferentially fluidized the cytofacial leaflet and concomitantly increased Na+-gradient-dependentd-glucose uptake, but decreased Na+, K+-dependentl-glutamic acid uptake in these membrane vesicles.In vitroaddition of benzyl alcohol (final concentration, 25 mm) preferentially fluidized the exofacial leaflet and decreased leucine aminopeptidase activity in these preparations. These results, therefore, demonstrate that the hemileaflets of human small intestinal brush-border membranes have different phospholipid compositions and fluidities. Alterations of either the exofacial or cytofacial leaflet fluidity, moreover, modulate protein-mediated activities in a distinct manner.