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XB-ART-43301
Cell Calcium 2011 Jul 01;501:36-41. doi: 10.1016/j.ceca.2011.04.008.
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Enhanced ER Ca2+ store filling by overexpression of SERCA2b promotes IP3-evoked puffs.

Yamasaki-Mann M , Parker I .


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Liberation of Ca(2+) from the endoplasmic reticulum (ER) through inositol trisphosphate receptors (IP(3)R) is modulated by the ER Ca(2+) content, and overexpression of SERCA2b to accelerate Ca(2+) sequestration into the ER has been shown to potentiate the frequency and amplitude of IP(3)-evoked Ca(2+) waves in Xenopus oocytes. Here, we examined the effects of SERCA overexpression on the elementary IP(3)-evoked puffs to elucidate whether ER [Ca(2+)] may modulate IP(3)R function via luminal regulatory sites in addition to simply determining the size of the available store and electrochemical driving force for Ca(2+) release. SERCA2b and Ca(2+) permeable nicotinic plasmalemmal channels were expressed in oocytes, and hyperpolarizing pulses were delivered to induce Ca(2+) influx and thereby load ER stores. Puffs evoked by photoreleased IP(3) were significantly potentiated in terms of numbers of responding sites, frequency and amplitude following transient Ca(2+) influx in SERCA-overexpressing cells, whereas little change was evident with SERCA overexpression alone or following Ca(2+) influx in control cells not overexpressing SERCA. Intriguingly, we observed the appearance of a new population of puffs that arose after long latencies and had prolonged durations supporting the notion of luminal regulation of IP(3)R gating kinetics.

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Berridge, Calcium signalling: dynamics, homeostasis and remodelling. 2003, Pubmed