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Structural and functional analyses were used to investigate the regulation of the inositol 1,4,5-trisphosphate (InsP3) receptor (InsP3R) by Ca2+. To define the structural determinants for Ca2+ binding, cDNAs encoding GST fusion proteins that covered the complete linear cytosolic sequence of the InsP3R-1 were expressed in bacteria. The fusion proteins were(More)
Striated muscle represents one of the best models for studies on Ca(2+) signalling. However, although much is known on the localisation and molecular interactions of the ryanodine receptors (RyRs), far less is known on the localisation and on the molecular interactions of the inositol trisphosphate receptors (InsP(3)Rs) in striated muscle cells. Recently,(More)
To study the Ca2+ regulation of the inositol 1,4,5-trisphosphate receptor (InsP3R) at the molecular level, we expressed various cytosolic and luminal regions of the mouse type I InsP3R as glutathione S-transferase fusion proteins. 45Ca2+ and ruthenium red overlay studies and Stains-all spectra and staining revealed both a cytosolic and a luminal Ca2+(More)
Inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) induces Ca2+ oscillations and waves in Xenopus laevis oocytes. Microsomes from oocytes exhibit high-affinity binding for Ins(1,4,5)P3, and demonstrate Ins(1,4,5)P3-induced Ca2+ release. The Ins(1,4,5)P3 receptor (InsP3R) was purified from oocyte microsomes as a large tetrameric complex and shown to have a monomer(More)
Golgi antiapoptotic protein (GAAP) is a novel regulator of cell death that is highly conserved in eukaryotes and present in some poxviruses, but its molecular mechanism is unknown. Given that alterations in intracellular Ca(2+) homeostasis play an important role in determining cell sensitivity to apoptosis, we investigated if GAAP affected Ca(2+) signaling.(More)
The inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) is a universal intracellular Ca2+-release channel. It is activated after cell stimulation and plays a crucial role in the initiation and propagation of the complex spatio-temporal Ca2+ signals that control cellular processes as different as fertilization, cell division, cell migration, differentiation,(More)
During maturation, mammalian oocytes undergo a series of changes that prepare them for fertilization. These events are regulated by kinases, most notably histone H1 and mitogen-activated protein kinase. Intracellular calcium ([Ca2+]i) oscillations participate in oocyte signaling, and it has been postulated that they play a role in oocyte maturation. In(More)
Binding of ATP to the inositol 1,4,5-trisphosphate receptor (IP(3)R) results in a more pronounced Ca(2+)release in the presence of inositol 1,4,5-trisphosphate (IP(3)). Two recently published studies demonstrated a different ATP sensitivity of IP(3)-induced Ca(2+)release in cell types expressing different IP(3)R isoforms. Cell types expressing mainly(More)
Calreticulin is a Ca2+-binding chaperone in the endoplasmic reticulum (ER), and calreticulin gene knockout is embryonic lethal. Here, we used calreticulin-deficient mouse embryonic fibroblasts to examine the function of calreticulin as a regulator of Ca2+ homeostasis. In cells without calreticulin, the ER has a lower capacity for Ca2+ storage, although the(More)
The inositol 1,4,5-trisphosphate receptor (IP3R) is an intracellular Ca2+ channel that is for the largest part expressed in the endoplasmic reticulum. Its precise subcellular localization is an important factor for the correct initiation and propagation of Ca2+ signals. The relative position of the IP3Rs, and thus of the IP3-sensitive Ca2+ stores, to(More)