Nakatsu Fubito, Ohno Hiroshi
Division of Molecular Membrane Biology, Cancer Research Institute, Kanazawa University, 13-1 Takara-machi, Kanazawa 920-0934, Japan.
Cell Struct Funct. 2003 Oct;28(5):419-29. doi: 10.1247/csf.28.419.
Adaptor protein (AP) complexes are cytosolic heterotetramers that mediate the sorting of membrane proteins in the secretory and endocytic pathways. AP complexes are involved in the formation of clathrin-coated vesicles (CCVs) by recruiting the scaffold protein, clathrin. AP complexes also play a pivotal role in the cargo selection by recognizing the sorting signals within the cytoplasmic tail of integral membrane proteins. Six distinct AP complexes have been identified. AP-2 mediates endocytosis from the plasma membrane, while AP-1, AP-3 and AP-4 play a role in the endosomal/lysosomal sorting pathways. Moreover, tissue-specific sorting events such as the basolateral sorting in polarized epithelial cells and the biogenesis of specialized organelles including melanosomes and synaptic vesicles are also regulated by members of AP complexes. The application of a variety of methodologies have gradually revealed the physiological role of AP complexes.
衔接蛋白（AP）复合物是胞质异源四聚体，介导分泌途径和内吞途径中膜蛋白的分选。AP复合物通过招募支架蛋白网格蛋白参与网格蛋白包被小泡（CCV）的形成。AP复合物还通过识别整合膜蛋白细胞质尾部的分选信号在货物选择中起关键作用。已鉴定出六种不同的AP复合物。AP-2介导从质膜的内吞作用，而AP-1、AP-3和AP-4在内体/溶酶体分选途径中起作用。此外，组织特异性分选事件，如极化上皮细胞中的基底外侧分选以及包括黑素小体和突触小泡在内的特殊细胞器的生物发生，也受AP复合物成员的调节。各种方法的应用逐渐揭示了AP复合物的生理作用。
