Orci L, Perrelet A, Rothman J E
Department of Morphology, University of Geneva Medical School, 1211 Geneva 4, Switzerland.
Proc Natl Acad Sci U S A. 1998 Mar 3;95(5):2279-83. doi: 10.1073/pnas.95.5.2279.
Cis-Golgi cisternae have a higher freeze-fracture particle density than trans-cisternae. Transport vesicles neighboring cis or trans positions of the Golgi stack have a particle concentration comparable to that of the adjacent cisterna and the buds emerging from it. This implies that transport vesicles remain locally within the stack during their lifetime, near their origin, favoring a processive pattern of transport in which vesicle transfers occur preferentially between adjacent cisternae in the stack. A "string theory" is proposed to account for processive transport, in which a carpet of fibrous attachment proteins located at the surface of cisternae (the strings) prevent budded vesicles from diffusing away but still allow them to diffuse laterally, effectively limiting transfers to adjoining cisternae in the stack. Fibrous elements that multivalently connect otherwise free COPI-coated vesicles and uncoated transport vesicles to one or two cisternae simultaneously are discerned readily by electron microscopy. It is suggested that long, coiled coil, motif-rich, Golgi-specific proteins including p115, GM130, and possibly giantin, among others, function as the proposed strings.
顺面高尔基体潴泡的冷冻蚀刻颗粒密度高于反面潴泡。靠近高尔基体堆叠顺面或反面位置的运输小泡的颗粒浓度与相邻潴泡及其产生的芽的颗粒浓度相当。这意味着运输小泡在其生命周期内会停留在堆叠内靠近其起源的局部区域，有利于一种连续运输模式，即小泡转移优先发生在堆叠中相邻的潴泡之间。有人提出一种“串理论”来解释连续运输，其中位于潴泡表面的纤维附着蛋白地毯（串）可防止出芽的小泡扩散离开，但仍允许它们横向扩散，从而有效地限制了向堆叠中相邻潴泡的转移。通过电子显微镜很容易识别出多价连接原本游离的COP I被膜小泡和无被运输小泡与一个或两个潴泡的纤维成分。有人认为，包括p115、GM130以及可能还有巨蛋白等在内的长的、富含卷曲螺旋基序的高尔基体特异性蛋白起到了所提出的串的作用。
