Department of Cellular Biology and Center for Tropical and Global Emerging Diseases, University of Georgia, Athens 30602, USA.
Cell Calcium. 2011 Aug;50(2):113-9. doi: 10.1016/j.ceca.2011.05.012. Epub 2011 Jul 12.
Acidocalcisomes are acidic organelles containing calcium and a high concentration of phosphorus in the form of pyrophosphate (PP(i)) and polyphosphate (poly P). Organelles with these characteristics have been found from bacteria to human cells implying an early appearance and persistence over evolutionary time or their appearance by convergent evolution. Acidification of the organelles is driven by the presence of vacuolar proton pumps, one of which, the vacuolar proton pyrophosphatase, is absent in animals, where it is substituted by a vacuolar proton ATPase. A number of other pumps, antiporters, and channels have been described in acidocalcisomes of different species and are responsible for their internal content. Enzymes involved in the synthesis and degradation of PP(i) and poly P are present within the organelle. Acidocalcisomes function as storage sites for cations and phosphorus, and participate in PP(i) and poly P metabolism, calcium homeostasis, maintenance of intracellular pH, and osmoregulation. Experiments in which the acidocalcisome Ca(2+)-ATPase of different parasites were downregulated or eliminated, or acidocalcisome Ca(2+) was depleted revealed the importance of this store in Ca(2+) signaling needed for host invasion and virulence. Acidocalcisomes interact with other organelles in a number of organisms suggesting their association with the endosomal/lysosomal pathway, and are considered part of the lysosome-related group of organelles.
酸钙小体是含有钙的酸性细胞器，以焦磷酸（PP(i)）和多聚磷酸盐（多聚 P）的形式含有高浓度的磷。具有这些特征的细胞器已在从细菌到人类细胞的范围内被发现，这意味着它们在进化过程中很早就出现了，并一直存在，或者是通过趋同进化而出现的。细胞器的酸化是由液泡质子泵的存在驱动的，其中一种液泡质子焦磷酸酶在动物中不存在，动物中由液泡质子 ATP 酶取代。在不同物种的酸钙小体中已经描述了许多其他的泵、反向转运蛋白和通道，它们负责细胞器的内部内容。参与 PP(i)和多聚 P 合成和降解的酶存在于细胞器内。酸钙小体作为阳离子和磷的储存场所，参与 PP(i)和多聚 P 代谢、钙稳态、细胞内 pH 值维持和渗透调节。在不同寄生虫的酸钙小体 Ca(2+)-ATP 酶被下调或消除，或酸钙小体 Ca(2+)被耗尽的实验中，揭示了这个储存库在宿主入侵和毒力所需的 Ca(2+)信号中的重要性。酸钙小体与许多生物中的其他细胞器相互作用，表明它们与内体/溶酶体途径有关，并被认为是溶酶体相关细胞器群的一部分。
