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Title: Baseline cytosolic Ca2+ oscillations derived from a non-endoplasmic reticulum Ca2+ store
Authors: Missiaen, Ludwig
Van Acker, K
Parys, Jan
De Smedt, Humbert
Van Baelen, Kurt
Weidema, Adam Frederik
Vanoevelen, Jo
Raeymaekers, Luc
Renders, J
Callewaert, Geert
Rizzuto, R
Wuytack, Frank #
Issue Date: Oct-2001
Series Title: Journal of Biological Chemistry vol:276 issue:42 pages:39161-70
Abstract: Cytosolic Ca(2+) oscillations can be due to cycles of release and re-uptake of internally stored Ca(2+). To investigate the nature of these Ca(2+) stores, we expressed the Pmr1 Ca(2+) pump of Caenorhabditis elegans in COS-1 cells and pretreated the cells with thapsigargin to prevent Ca(2+) uptake by the sarco(endo)plasmic reticulum Ca(2+)-ATPase. Pmr1 co-localized with the Golgi-specific 58K protein and was targeted to a Ca(2+) store that was less leaky for Ca(2+) than the endoplasmic reticulum and whose inositol trisphosphate receptors were less sensitive to inositol trisphosphate and ATP than those in the endoplasmic reticulum. ATP-stimulated Pmr1-overexpressing cells responded after a latency to extracellular Ca(2+) with a regenerative Ca(2+) signal, which could be prevented by caffeine. They also produced very stable ilimaquinone-sensitive baseline Ca(2+) spikes, even in the presence of thapsigargin. Such responses never occurred in non-transfected cells or in cells that overexpressed the type-1 sarco(endo)plasmic reticulum Ca(2+)-ATPase. Abortive Ca(2+) spikes also occurred in histamine-stimulated untransfected HeLa cells pretreated with thapsigargin, and they too were inhibited by ilimaquinone. We conclude that the Pmr1-induced Ca(2+) store, which probably corresponds to the Golgi compartment, can play a crucial role in setting up baseline Ca(2+) spiking.
ISSN: 0021-9258
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Physiology Section (-)
Laboratory of Molecular and Cellular Signaling
Laboratory of Cellular Transport Systems
# (joint) last author

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