发布: 2017年11月20日第7卷第22期 DOI: 10.21769/BioProtoc.2450 浏览次数: 7582
评审: Gal HaimovichAnonymous reviewer(s)
Abstract
The aim of this protocol is to generate COPII-coated procollagen I (PC1) carriers in a cell-free reaction. The COPII-coated PC1 carriers were reconstituted from donor membrane, cytosol, purified recombinant COPII proteins, and nucleotides. This protocol describes the preparation of donor membrane and cytosol, the assembly of the reaction, and the isolation and detection of reconstituted COPII-coated carriers. This cell-free reaction can be used to test conditions that stimulate or suppress the packaging of PC1 into COPII-coated carriers.
Keywords: COPII (COPII)Background
The coat protein complex II (COPII) plays an essential role in transporting secretory cargos from the endoplasmic reticulum (ER) en route to the Golgi apparatus. The genes required for cargo traffic from the ER were discovered in genetic studies in yeast and the precise roles of the protein products of the genes required for vesicle budding were elucidated with the aid of a cell-free vesicle budding reaction supplemented with purified components (Novick et al., 1981; Kaiser et al., 1990; Barlowe et al., 1994). A similar reaction was developed to detect the role of COPII in cargo traffic from the ER in cultured mammalian cells (Kim et al., 2005). Mammalian COPII-coated vesicles are approximately 80-100 nm in diameter, which is seemingly too small to accommodate large secretory cargos such as the rigid 300 nm procollagen I (PC1) triple helical rod. Despite the potential size discrepancy, COPII is essential for the secretion of large cargos including PC1 (Boyadjiev et al., 2006). Recently, we reported the existence of bona fide large COPII-coated PC1 carriers, exceeding 300 nm in diameter, in cells evaluated by stochastic optical reconstruction microscopy (STORM), correlated light electron microscopy (CLEM) and live-cell imaging (Gorur et al., 2017). Cell-free COPII budding reactions that successfully reconstituted small COPII vesicles did not allow the detection of large COPII-coated PC1 carriers (Fromme and Schekman, 2005). Therefore, we devised an alternative vesicle budding protocol to allow the detection of PC1 packaged into large COPII vesicles as well as the characterization of both small and large COPII-coated vesicles. Using this new protocol, we showed that the capture of PC1 into large COPII vesicles requires COPII proteins and the GTPase activity of the COPII subunit SAR1 (Gorur et al., 2017).
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版权信息
© 2017 The Authors; exclusive licensee Bio-protocol LLC.
如何引用
Readers should cite both the Bio-protocol article and the original research article where this protocol was used:
分类
生物化学 > 脂质 > 脂质-蛋白互作
生物化学 > 蛋白质 > 分离和纯化
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