Burger M M, Schäfer T
Friedrich Miescher-Institute, Basel, Switzerland.
J Cell Biochem Suppl. 1998;30-31:103-10.
Maintenance of compartmental independence and diversity is part of the blueprint of the eukaryotic cell. The molecular composition of every organelle membrane is custom tailored to fulfill its unique tasks. It is retained by strict sorting and directional transport of newly synthesized cellular components by the use of specific transport vesicles. Temporally and spatially controlled membrane fission and fusion steps thus represent the basic process for delivery of both, membrane-bound and soluble components to their appropriate destination. This process is fundamental to cell growth, organelle inheritance during cell division, uptake and intracellular transport of membrane-bound and soluble molecules, and neuronal communication. The latter process has become one of the best studied examples in terms of regulatory mechanisms of membrane interactions. It has been dissected into the stages of transmitter vesicle docking, priming, and fusion: Specificity of membrane interactions depends on interactions between sets of organelle-specific membrane proteins. Priming of the secretory apparatus is an ATP-dependent process involving proteins and membrane phospholipids. Release of vesicle content is triggered by a rise in intracellular free Ca2+ levels that relieves a block previously established between the membranes poised to fuse. Neurotransmitter release is a paradigm of highly regulated intracellular membrane interaction and molecular mechanisms for this phenomenon begin to be delineated.
维持区室的独立性和多样性是真核细胞蓝图的一部分。每个细胞器膜的分子组成都是为完成其独特任务而量身定制的。通过使用特定的运输囊泡对新合成的细胞成分进行严格的分选和定向运输来维持这种组成。因此，在时间和空间上受到控制的膜分裂和融合步骤代表了将膜结合成分和可溶性成分输送到其适当目的地的基本过程。这一过程对于细胞生长、细胞分裂期间的细胞器遗传、膜结合分子和可溶性分子的摄取及细胞内运输以及神经元通讯至关重要。就膜相互作用的调控机制而言，后一过程已成为研究得最为透彻的例子之一。它已被细分为递质囊泡对接、引发和融合阶段：膜相互作用的特异性取决于细胞器特异性膜蛋白组之间的相互作用。分泌装置的引发是一个依赖ATP的过程，涉及蛋白质和膜磷脂。囊泡内容物的释放由细胞内游离Ca2+水平的升高触发，这解除了先前在准备融合的膜之间建立的阻断。神经递质释放是高度调控的细胞内膜相互作用的范例，并且这一现象的分子机制开始得到阐明。
