Arvan P, Castle D
Division of Endocrinology and Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Biochem J. 1998 Jun 15;332 ( Pt 3)(Pt 3):593-610. doi: 10.1042/bj3320593.
Secretory granules are specialized intracellular organelles that serve as a storage pool for selected secretory products. The exocytosis of secretory granules is markedly amplified under physiologically stimulated conditions. While granules have been recognized as post-Golgi carriers for almost 40 years, the molecular mechanisms involved in their formation from the trans-Golgi network are only beginning to be defined. This review summarizes and evaluates current information about how secretory proteins are thought to be sorted for the regulated secretory pathway and how these activities are positioned with respect to other post-Golgi sorting events that must occur in parallel. In the first half of the review, the emerging role of immature secretory granules in protein sorting is highlighted. The second half of the review summarizes what is known about the composition of granule membranes. The numerous similarities and relatively limited differences identified between granule membranes and other vesicular carriers that convey products to and from the plasmalemma, serve as a basis for examining how granule membrane composition might be established and how its unique functions interface with general post-Golgi membrane traffic. Studies of granule formation in vitro offer additional new insights, but also important challenges for future efforts to understand how regulated secretory pathways are constructed and maintained.
分泌颗粒是一种特殊的细胞内细胞器，作为特定分泌产物的储存库。在生理刺激条件下，分泌颗粒的胞吐作用会显著增强。尽管颗粒被认为是高尔基体后载体已有近40年，但从反式高尔基体网络形成颗粒所涉及的分子机制才刚刚开始被阐明。这篇综述总结并评估了关于分泌蛋白如何被分选进入调节性分泌途径，以及这些活动相对于必须同时发生的其他高尔基体后分选事件是如何定位的当前信息。在综述的前半部分，强调了未成熟分泌颗粒在蛋白质分选中的新作用。综述的后半部分总结了关于颗粒膜组成的已知信息。在颗粒膜与其他将产物转运至质膜和从质膜转运出的囊泡载体之间发现的众多相似之处和相对有限的差异，为研究颗粒膜组成如何建立以及其独特功能如何与一般高尔基体后膜运输相互作用提供了基础。体外颗粒形成的研究提供了额外的新见解，但对于未来理解调节性分泌途径如何构建和维持的努力也提出了重要挑战。
