Wang S, Hsu S C
Department of Cell Biology and Neuroscience, Rutgers University, Nelson Biological Laboratories, 604 Allison Rd, D419, Piscataway, NJ 08854, USA.
Biochem Soc Trans. 2006 Nov;34(Pt 5):687-90. doi: 10.1042/BST0340687.
Exocytosis is a highly ordered vesicle trafficking pathway that targets proteins to the plasma membrane for membrane addition or secretion. Research over the years has discovered many proteins that participate at various stages in the mammalian exocytotic pathway. At the early stage of exocytosis, co-atomer proteins and their respective adaptors and GTPases have been shown to play a role in the sorting and incorporation of proteins into secretory vesicles. At the final stage of exocytosis, SNAREs (soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor) and SNARE-associated proteins are believed to mediate the fusion of secretory vesicles at the plasma membrane. There are multiple events that may occur between the budding of secretory vesicles from the Golgi and the fusion of these vesicles at the plasma membrane. The most obvious and best-known event is the transport of secretory vesicles from Golgi to the vicinity of the plasma membrane via microtubules and their associated motors. At the vicinity of the plasma membrane, however, it is not clear how vesicles finally dock and fuse with the plasma membrane. Identification of proteins involved in these events should provide important insights into the mechanisms of this little known stage of the exocytotic pathway. Currently, a protein complex, known as the sec6/8 or the exocyst complex, has been implicated to play a role at this late stage of exocytosis.
胞吐作用是一种高度有序的囊泡运输途径，它将蛋白质靶向运输到质膜，用于膜的添加或分泌。多年来的研究发现了许多参与哺乳动物胞吐途径不同阶段的蛋白质。在胞吐作用的早期，外套蛋白及其各自的衔接蛋白和GTP酶已被证明在蛋白质分选和纳入分泌囊泡的过程中发挥作用。在胞吐作用的最后阶段，SNAREs（可溶性N-乙基马来酰亚胺敏感融合蛋白附着蛋白受体）和SNARE相关蛋白被认为介导分泌囊泡在质膜处的融合。在分泌囊泡从高尔基体出芽到这些囊泡在质膜处融合之间可能会发生多个事件。最明显且最广为人知的事件是分泌囊泡通过微管及其相关的马达从高尔基体运输到质膜附近。然而，在质膜附近，囊泡最终如何停靠并与质膜融合尚不清楚。鉴定参与这些事件的蛋白质应该能为这个胞吐途径中鲜为人知阶段的机制提供重要见解。目前，一种称为sec6/8或外排体复合物的蛋白质复合物被认为在胞吐作用的这个后期阶段发挥作用。
