Effects of PMCA and SERCA pump overexpression on the kinetics of cell Ca(2+) signalling |
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Authors: | Brini M Bano D Manni S Rizzuto R Carafoli E |
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Affiliation: | Department of Biochemistry and Center for the Study of Biomembranes of the National Research Council (CNR), University of Padova, Viale G. Colombo, 3, 35121 Padova, Italy. brini@civ.bio.unipd.it |
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Abstract: | The dynamic interactions of the main pathways for active Ca(2+) transport have been analysed in living cells by altering the expression of their components. The plasma membrane (PMCA) and the endoplasmic reticulum (ER) (SERCA) Ca(2+) pumps were transiently overexpressed in CHO cells, and the Ca(2+) homeostasis in the subcellular compartments was investigated using specifically targeted chimaeras of the Ca(2+)- sensitive photoprotein aequorin. In resting cells, overexpression of the PMCA and SERCA pumps caused a reduction and an increase in ER [Ca(2+)] levels, respectively, while no significant differences were detected in cytosolic and mitochondrial [Ca(2+)]. Upon stimulation with an inositol 1,4, 5-trisphosphate (IP(3))-generating agonist, the amplitude of the mitochondrial and cytosolic Ca(2+) rises correlated with the ER [Ca(2+)] only up to a threshold value, above which the feedback inhibition of the IP(3) channel by Ca(2+) appeared to be limiting. |
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