Eukaryotic cilia/flagella are ideal organelles for the analysis of membrane trafficking, membrane assembly, and the functions of a variety of signal transduction molecules. Cilia are peninsular organelles and the membrane lipids, membrane proteins, and microtubular-associated components are selectively transported into cilia through the region formed by the basal body/transition region and tightly associated ciliary membrane. Cilia can be isolated from many organisms without disrupting cells and many will rapidly regenerate cilia (with the ciliary membrane lipids and proteins) to replace those that are released. Despite their ease of isolation, we have relatively little understanding of the mechanisms that regulate lipid and protein transport into ciliary membranes (Pazour and Bloodgood, 2008; Bloodgood, 2009; Bloodgood, 2012).Chlamydomonas flagella shed membrane vesicles, also called ectosomes (Wood et al., 2013) from flagellar tips and these vesicles can be purified from the culture medium without damaging or deflagellating cells (McLean et al., 1974; Bergman et al., 1975; Snell, 1976; Kalshoven et al., 1990). Based on a comparison of biotinylated proteins on the shed vesicles with biotinylated proteins isolated from purified flagella and cell bodies, the ectosomes contain most, but not all, flagellar surface proteins and none of the major cell body proteins (Dentler, 2013). Although ectosomes have only been purified from Chlamydomonas cells, preliminary evidence indicates that similar vesicles are released from Tetrahymena cilia (Dentler, unpublished). Flagellar (and ciliary) membranes or membrane proteins also can be released from purified flagella/cilia. Most membrane proteins can be solubilized by extracting purified cilia with nonionic detergent [Triton X-100 or X-114 or Nonidet P-40 (NP-40)] and pelleting the microtubules (axonemes). However, not all membranes are released by detergent (Dentler, 1980) and the supernatant also contains all of the flagellar proteins that are not attached to the microtubules. Intact membrane vesicles can be released from flagella by agitation of flagella, often with low concentrations of nonionic detergents or freeze-thawing (Witman et al., 1972; Snell, 1976; Dentler, 1980; Dentler, 1995; Bloodgood and May, 1982; Pasquale and Goodenough, 1987; Iomini et al., 2006; Huang et al., 2007). Once released, they can be purified from axonemes by differential centrifugation.Each of these methods may enrich for different populations of axonemal and membrane proteins and lipids. The different solubility of membranes may reveal local differences in lipid or protein composition (Bloodgood, 2009). The ectosomes contain most but not all surface proteins found on purified Chlamydomonas flagella (Dentler, 2013). The ectosomes vesicles may be enriched in different soluble flagellar proteins than those trapped as vesicles are released from purified flagella. The detergent-solubilized “membrane+matrix” will contain all soluble membrane proteins as well as all of the soluble proteins in the flagellar compartment. In this paper, a method to purify ectosomes vesicles released from the tips of living Chlamydomonas cells is presented as are two methods to release flagellar membrane vesicles and proteins from purified flagella., 真核纤毛/鞭毛是分析膜运输,膜组装和各种信号转导分子的功能的理想细胞器。纤毛是半岛细胞器,并且膜脂质,膜蛋白和微管相关组分通过由基底体/过渡区和紧密相关的睫状膜形成的区域选择性地转运到纤毛中。纤毛可以从许多生物体中分离而不破坏细胞,并且许多将快速再生纤毛(具有睫状膜脂质和蛋白质)以替代释放的纤毛。尽管它们容易分离,但我们对调节脂质和蛋白质转运到睫状膜的机制的理解相对较少(Pazour和Bloodgood,2008; Bloodgood,2009; Bloodgood,2012)。 鞭毛脱落的膜囊泡,也称为来自鞭毛尖端的卵母细胞(Wood等人,2013),并且可以从培养基中纯化这些囊泡而没有损伤或去鞭毛细胞(McLean等人, ,1974; Bergman et al。,1975; Snell,1976; Kalshoven et al。,1990)。基于脱落囊泡上的生物素化蛋白质与从纯化鞭毛和细胞体分离的生物素化蛋白质的比较,外周体含有大多数但不是全部的鞭毛表面蛋白质,并且没有主要的细胞体蛋白质(Dentler,2013)。虽然ectosomes只从衣原体细胞中纯化,但初步证据表明类似的囊泡从四膜虫纤毛释放(Dentler,未发表)。 鞭毛(和睫状体)膜或膜蛋白也可以从纯化的鞭毛/纤毛释放。大多数膜蛋白可以通过用非离子去污剂[Triton X-100或X-114或Nonidet P-40(NP-40)]提取纯化的纤毛并将微管(轴突)造粒来溶解。然而,不是所有的膜都被去污剂释放(Dentler,1980),并且上清液还包含所有未附着到微管的鞭毛蛋白。通过搅动鞭毛,通常使用低浓度的非离子型洗涤剂或冷冻融化,可以从鞭毛中释放完整的膜囊泡(Witman等人,1972; Snell,1976; Dentler,1980 ; Dentler,1995; Bloodgood和May,1982; Pasquale和Goodenough,1987; Iomini等人,2006; Huang等人,2007)。一旦释放,可以通过差速离心从轴突中纯化它们。这些方法中的每一种可以富集轴突和膜蛋白和脂质的不同群体。膜的不同溶解度可以揭示脂质或蛋白质组成的局部差异(Bloodgood,2009)。外来体含有在纯化的衣藻鞭毛上发现的大多数但不是全部表面蛋白(Dentler,2013)。外来体囊泡可以富集在不同的可溶性鞭毛蛋白中,而不是当从纯化的鞭毛中释放囊泡时捕获的那些。洗涤剂增溶的"膜+基质"将包含鞭毛区室中的所有可溶性膜蛋白以及所有可溶性蛋白。 在本文中,提出了从活的衣藻细胞的末端释放的外来体囊泡的方法,以提供从纯化的鞭毛中释放鞭毛膜囊泡和蛋白质的两种方法。
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