Plattner Helmut
Department of Biology, University of Konstanz , Konstanz , Germany.
Crit Rev Microbiol. 2015 Jun;41(2):218-27. doi: 10.3109/1040841X.2013.821650. Epub 2013 Aug 6.
The contractile vacuole complex (CVC) of freshwater protists sequesters the excess of water and ions (Ca(2+)) for exocytosis cycles at the pore. Sequestration is based on a chemiosmotic proton gradient produced by a V-type H(+)-ATPase. So far, many pieces of information available have not been combined to a comprehensive view on CVC biogenesis and function. One main function now appears as follows. Ca(2+)-release channels, type inositol 1,4,5-trisphosphate receptors (InsP3R), may serve for fine-tuning of local cytosolic Ca(2+) concentration and mediate numerous membrane-to-membrane interactions within the tubular spongiome meshwork. Such activity is suggested by the occurrence of organelle-specific soluble N-ethylmaleimide sensitive factor attachment protein receptor (SNARE) and Ras-related in brain (Rab) proteins, which may regulate functional requirements. For tubulation, F-Bin-amphiphysin-Rvs (F-BAR) proteins are available. In addition, there is indirect evidence for the occurrence of H(+)/Ca(2+) exchangers (to sequester Ca(2+)) and mechanosensitive Ca(2+)-channels (for signaling the filling sate). The periodic activity of the CVC may be regulated by the mechanosensitive Ca(2+)-channels. Such channels are known to colocalize with and to be functionally supported by stomatins, which were recently detected in the CVC. A Kif18-related kinesin motor protein might control the length of radial arms. Two additional InsP3-related channels and several SNAREs are associated with the pore. De novo organelle biogenesis occurs under epigenetic control during mitotic activity and may involve the assembly of γ-tubulin, centrin, calmodulin and a never in mitosis A-type (NIMA) kinase - components also engaged in mitotic processes.
淡水原生生物的收缩泡复合体（CVC）在孔隙处隔离过量的水和离子（Ca(2+)），用于胞吐循环。隔离基于V型H(+)-ATP酶产生的化学渗透质子梯度。到目前为止，现有的许多信息尚未整合为关于CVC生物发生和功能的全面观点。现在一个主要功能如下。Ca(2+)释放通道，即1,4,5-三磷酸肌醇受体（InsP3R）类型，可能用于微调局部胞质Ca(2+)浓度，并介导管状海绵体网络内众多膜与膜之间的相互作用。细胞器特异性可溶性N-乙基马来酰亚胺敏感因子附着蛋白受体（SNARE）和脑中Ras相关蛋白（Rab）的出现表明了这种活性，它们可能调节功能需求。对于微管形成，有F-Bin-发动蛋白-Rvs（F-BAR）蛋白。此外，有间接证据表明存在H(+)/Ca(2+)交换器（用于隔离Ca(2+)）和机械敏感Ca(2+)通道（用于信号填充状态）。CVC的周期性活动可能由机械敏感Ca(2+)通道调节。已知此类通道与 stomatins共定位并在功能上得到其支持，最近在CVC中检测到了stomatins。一种与Kif18相关的驱动蛋白运动蛋白可能控制径向臂的长度。另外两个与InsP3相关的通道和几个SNARE与孔隙相关。从头细胞器生物发生在有丝分裂活动期间受表观遗传控制，可能涉及γ-微管蛋白、中心蛋白、钙调蛋白和一种有丝分裂A 型（NIMA）激酶的组装——这些成分也参与有丝分裂过程。
