Ultrastructural localization of adenosine triphosphatase activity in HeLa cells at various stages of the cell cycle |
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Authors: | Dr Sanjida Mughal Abdullatif A Al-Bader Alfred Cuschieri Bassim Kharbat |
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Institution: | (1) Department of Anatomy, Faculty of Medicine, University of Kuwait, Kuwait;(2) Department of Pathology, Faculty of Medicine, University of Kuwait, Kuwait;(3) Present address: Department of Anatomy, University of Malta, Msida, Malta |
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Abstract: | Summary HeLa cells in a monolayer culture were synchronized to S, G2 and mitotic phases by use of excess (2.5 mM) deoxythymidine double-block technique. The localizations of Ca++-activated adenosine triphosphatase (ATPase) at different phases of the cell cycle were studied using light and electron-microscopic histochemical techniques, and microphotometric comparisons of the densities of reaction products. Enzyme reaction product was always localized in the endoplasmic reticulum, nuclear membrane, mitochondria and Golgi apparatus, but there were qualitative and quantitative differences related to the phases of the cell cycle. In S phase the activity was mainly concentrated in a perinuclear area of the cytoplasm whereas in G2 and mitosis the activity was scattered throughout the cell. The total activity per cell was maximal in G2, was less in S phase and least in mitosis. Activity in the mitochondria and endoplasmic reticulum was distinctly less in mitosis than in other phases of the cell cycle. The mitochondrial ATPase differed from the ATPase at other sites in ion dependence and sensitivity to oligomycin. The results suggest that there may be several distinct ATPases in proliferating cells. |
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Keywords: | Adenosine triphosphatase Ca++-ATPase Histochemical localization Cell cycle HeLa cells |
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