Pol A, Calvo M, Lu A, Enrich C
Departament de Biologia Cellular, Institut de Investigacions Biomèdiques August Pi i Sunyer, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain.
Hepatology. 1999 Jun;29(6):1848-57. doi: 10.1002/hep.510290602.
The sinusoidal plasma membrane of the hepatocyte is organized into functional and structural microdomains whose origin, maintenance, and functioning are closely related with the endocytic compartment. Three different subcellular fractions, from rat liver, containing caveolin-1, the structural protein of caveolae, were morphologically and biochemically characterized. A caveolae-enriched plasma membrane fraction (CEF), contains large membrane structures surrounding attached internal plasmalemmal vesicles; the receptor-recycling compartment (RRC), contains tubules and vesicles with similar morphology to the internal vesicles observed by electron microscopy in CEF; and finally, caveolin-1 was also detected in early-sorting endosomes (CURL, compartment of uncoupling receptors and ligands). In this study, we show that following an intravenous administration of retinol-binding protein (RBP), there was a redistribution of caveolin-1 from the plasma membrane (CEF) to intracellular endocytic compartments (RRC and early-sorting endosomes). Thus, these results indicate that, in the hepatocyte, caveolae are dynamic structures actively interacting with the endocytic compartment.
肝细胞的窦状质膜被组织成功能和结构微区，其起源、维持和功能与内吞区室密切相关。对来自大鼠肝脏的三种不同亚细胞组分进行了形态学和生物化学表征，这些组分含有小窝蛋白-1（小窝的结构蛋白）。富含小窝的质膜组分（CEF）含有围绕附着的内部质膜小泡的大膜结构；受体回收区室（RRC）含有形态与在CEF中通过电子显微镜观察到的内部小泡相似的小管和小泡；最后，在早期分选内体（CURL，解偶联受体和配体的区室）中也检测到了小窝蛋白-1。在本研究中，我们表明，静脉注射视黄醇结合蛋白（RBP）后，小窝蛋白-1从质膜（CEF）重新分布到细胞内吞区室（RRC和早期分选内体）。因此，这些结果表明，在肝细胞中，小窝是与内吞区室积极相互作用的动态结构。
