Acidosome
Acidosomes are cell organelles in eukaryotic cells that are bounded by a simple membrane and are characterized by their acidic content. They were first for the paramecium Paramecium multimicronucleatum described, but subsequently in other paramecium found types, and may also occur in other ciliates ( Ciliophora, Ciliata before). Acidosomes have also been described for the slime mold Dictyostelium discoideum , but whether these are homologous to the organelles from Paramecium is unclear.
Function and biogenesis in Paramecium
When extracellular material is absorbed, a digestive vacuole , phagosome , forms in Paramecium at the cell mouth ( cytostome ) , near which several acidosomes accumulate. After the phagosome has been separated off and during its migration to the rear cell pole, the acidosomes fuse with it and acidify it in this way, so that the pH value drops from 7 to 3 there. The acidified phagosomes can then fuse with lysosomes , which contribute the acid-dependent hydrolases required to digest the ingested material .
Acidosomes are formed in Paramecium on the trans-Golgi network as pre-acidosomes, which then mature through fusion with other vesicles .
Acidosomes in Dictyostelium discoideum
The organelles found in Dictyostelium and known as acidosomes are characterized by a high content of V-ATPase , which probably brings about acidification of the organelles. A similar biogenesis and function as for the acidosomes of Paramecium is assumed.
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- ↑ a b Richard D. Allen, Le Ma, Agnes K. Fok: Acidosomes: recipients of multiple sources of membrane and cargo during development and maturation . In: Journal of Cell Science . tape 106 , 1993, pp. 411-422 (English, biologists.org [PDF]).
- ↑ Kathleen V. Nolta, Harish Padh, Theodore L. Stecks: Acidosomes from Dictyostelium - Initial biochemical characterization . In: The journal of Biological Chemistry . tape 266 , no. 27 , 1991, pp. 18318–18323 (English, jbc.org [PDF]).