Luminal calcium regulation of calcium release from sarcoplasmic reticulum

1995 ◽  
Vol 15 (5) ◽  
pp. 387-397 ◽  
Author(s):  
Cecilia Hidalgo ◽  
Paulina Donoso
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Concentration ◽  
Calcium Release ◽  
Single Channel ◽  
Release Rates ◽  
Calcium Release Channels ◽  
Channel Opening ◽  
Inositol 1,4,5 Trisphosphate ◽  
Luminal Calcium ◽  
Trisphosphate Receptor

This article discusses how changes in luminal calcium concentration affect calcium release rates from triad-enriched sarcoplasmic reticulum vesicles, as well as single channel opening probability of the ryanodine receptor/calcium release channels incorporated in bilayers. The possible participation of calsequestrin, or of other luminal proteins of sarcoplasmic reticulum in this regulation is addressed. A comparison with the regulation by luminal calcium of calcium release mediated by the inositol 1,4,5-trisphosphate receptor/calcium channel is presented as well.

scholarly journals Divalent cation activation and inhibition of single calcium release channels from sheep cardiac sarcoplasmic reticulum.

1990 ◽  
Vol 95 (5) ◽  
pp. 981-1005 ◽  
Author(s):  
R H Ashley ◽  
A J Williams
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Lipid Bilayers ◽  
Calcium Release ◽  
Single Channel ◽  
Fluctuation Analysis ◽  
Open Probability ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Channel Opening ◽  
Lifetime Analysis ◽  
Single Channel Currents

Single Ca2+ release channels from vesicles of sheep cardiac junctional sarcoplasmic reticulum have been incorporated into uncharged planar lipid bilayers. Single-channel currents were recorded from Ca2(+)-activated channels that had a Ca2+ conductance of approximately 90 pS. Channel open probability increased sublinearly as the concentration of free Ca2+ was raised at the myoplasmic face, and without additional agonists the channels could not be fully activated even by 100 microM free Ca2+. Lifetime analysis revealed a minimum of two open and three closed states, and indicates that Ca2+ activated the channels by interacting with at least one of the closed states to increase the rate of channel opening. Correlations between adjacent lifetimes suggested there were at least two pathways between the open- and closed-state aggregates. An analysis of bursting behavior also revealed correlations between successive burst lengths and the number of openings per burst. The latter had two geometric components, providing additional evidence for at least two open states. One component appeared to comprise unit bursts, and the lifetime of most of these fell within the dominant shorter open-time distribution associated with over 90% of all openings. A cyclic gating scheme is proposed, with channel activation regulated by the binding of Ca2+ to a closed conformation of the channel protein. Mg2+ may inhibit activation by competing for this binding site, but lifetime and fluctuation analysis suggested that once activated the channels continue to gate normally.

scholarly journals Isoform-specific Regulation of the Inositol 1,4,5-Trisphosphate Receptor by O-Linked Glycosylation

2011 ◽  
Vol 286 (18) ◽  
pp. 15688-15697 ◽  
Author(s):  
Patricia Bimboese ◽  
Craig J. Gibson ◽  
Stefan Schmidt ◽  
Wanqing Xiang ◽  
Barbara E. Ehrlich
Keyword(s):  
Intracellular Calcium ◽  
Cell Line ◽  
Calcium Release ◽  
Single Channel ◽  
Open Probability ◽  
Functional Changes ◽  
Inositol 1,4,5 Trisphosphate ◽  
Cholangiocarcinoma Cell ◽  
Specific Regulation ◽  
Trisphosphate Receptor

The inositol 1,4,5-trisphosphate receptor (InsP3R), an intracellular calcium channel, has three isoforms with >65% sequence homology, yet the isoforms differ in their function and regulation by post-translational modifications. We showed previously that InsP3R-1 is functionally modified by O-linked β-N-acetylglucosamine glycosylation (O-GlcNAcylation) (Rengifo, J., Gibson, C. J., Winkler, E., Collin, T., and Ehrlich, B. E. (2007) J. Neurosci. 27, 13813–13821). We now report the effect of O-GlcNAcylation on InsP3R-2 and InsP3R-3. Analysis of AR4-2J cells, a rat pancreatoma cell line expressing predominantly InsP3R-2, showed no detectable O-GlcNAcylation of InsP3R-2 and no significant functional changes despite the presence of the enzymes for addition (O-β-N-acetylglucosaminyltransferase) and removal (O-β-N-acetylglucosaminidase) of the monosaccharide. In contrast, InsP3R-3 in Mz-ChA-1 cells, a human cholangiocarcinoma cell line expressing predominantly InsP3R-3, was functionally modified by O-GlcNAcylation. Interestingly, the functional impact of O-GlcNAcylation on the InsP3R-3 channel was opposite the effect measured with InsP3R-1. Addition of O-GlcNAc by O-β-N-acetylglucosaminyltransferase increased InsP3R-3 single channel open probability. Incubation of Mz-ChA-1 cells in hyperglycemic medium caused an increase in the InsP3-dependent calcium release from the endoplasmic reticulum. The dynamic and inducible nature of O-GlcNAcylation and the InsP3R isoform specificity suggest that this form of modification of InsP3R and subsequent changes in intracellular calcium transients are important in physiological and pathophysiological processes.

scholarly journals Bcl-2 functionally interacts with inositol 1,4,5-trisphosphate receptors to regulate calcium release from the ER in response to inositol 1,4,5-trisphosphate

2004 ◽  
Vol 166 (2) ◽  
pp. 193-203 ◽  
Author(s):  
Rui Chen ◽  
Ignacio Valencia ◽  
Fei Zhong ◽  
Karen S. McColl ◽  
H. Llewelyn Roderick ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Calcium Concentration ◽  
Calcium Release ◽  
Cytosolic Calcium ◽  
Open Probability ◽  
Apoptotic Protein ◽  
Inositol 1,4,5 Trisphosphate ◽  
A Cell ◽  
Luminal Calcium ◽  
Blue Native

Inositol 1,4,5-trisphosphate (InsP3) receptors (InsP3Rs) are channels responsible for calcium release from the endoplasmic reticulum (ER). We show that the anti-apoptotic protein Bcl-2 (either wild type or selectively localized to the ER) significantly inhibited InsP3-mediated calcium release and elevation of cytosolic calcium in WEHI7.2 T cells. This inhibition was due to an effect of Bcl-2 at the level of InsP3Rs because responses to both anti-CD3 antibody and a cell-permeant InsP3 ester were decreased. Bcl-2 inhibited the extent of calcium release from the ER of permeabilized WEHI7.2 cells, even at saturating concentrations of InsP3, without decreasing luminal calcium concentration. Furthermore, Bcl-2 reduced the open probability of purified InsP3Rs reconstituted into lipid bilayers. Bcl-2 and InsP3Rs were detected together in macromolecular complexes by coimmunoprecipitation and blue native gel electrophoresis. We suggest that this functional interaction of Bcl-2 with InsP3Rs inhibits InsP3R activation and thereby regulates InsP3-induced calcium release from the ER.

scholarly journals Effect of adenine nucleotides on myo-inositol-1,4,5-trisphosphate-induced calcium release

1997 ◽  
Vol 325 (3) ◽  
pp. 661-666 ◽  
Author(s):  
Ludwig MISSIAEN ◽  
Jan B. PARYS ◽  
Humbert DE SMEDT ◽  
Ilse SIENAERT ◽  
Henk SIPMA ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Binding Site ◽  
Calcium Release ◽  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Release Process ◽  
A7r5 Cells ◽  
Channel Opening ◽  
Inositol 1,4,5 Trisphosphate

The effects of a whole series of adenine nucleotides on Ins(1,4,5)P3-induced Ca2+ release were characterized in permeabilized A7r5 smooth-muscle cells. Several adenine nucleotides activated the Ins(1,4,5)P3 receptor. It was observed that 3′-phosphoadenosine 5′-phosphosulphate, CoA, di(adenosine-5′)tetraphosphate (Ap4A) and di(adenosine-5′)pentaphosphate (Ap5A) were more effective than ATP. Ap4A and Ap5A also interacted with a lower EC50 than ATP. In order to find out how these adenine nucleotides affected Ins(1,4,5)P3-induced Ca2+ release, we have measured their effect on the response of permeabilized A7r5 cells to a progressively increasing Ins(1,4,5)P3 concentration. Stimulatory ATP and Ap5A concentrations had no effect on the threshold Ins(1,4,5)P3 concentration for initiating Ca2+ release, but they stimulated Ca2+ release in the presence of supra-threshold Ins(1,4,5)P3 concentrations by increasing the co-operativity of the release process. Inhibition of the Ins(1,4,5)P3-induced Ca2+ release at higher ATP concentrations was associated with a further increase in co-operativity and also with a shift in threshold towards higher Ins(1,4,5)P3 concentrations. ATP had no effect on the non-specific Ca2+ leak in the absence of Ins(1,4,5)P3. We conclude that the adenine-nucleotide-binding site can be activated by many different adenine nucleotides. Binding of these compounds to the transducing domain of the Ins(1,4,5)P3 receptor increases the efficiency of transmitting Ins(1,4,5)P3 binding to channel opening. The inhibition by high ATP concentrations is exerted at a different site, related to Ins(1,4,5)P3 binding.

Partial calcium release in response to submaximal inositol 1,4,5-trisphosphate receptor activation

1994 ◽  
Vol 98 (2) ◽  
pp. 147-156 ◽  
Author(s):  
Ludwig Missiaen ◽  
Jan B. Parys ◽  
Humbert De Smedt ◽  
Masahiro Oike ◽  
Rik Casteels
Keyword(s):  
Calcium Release ◽  
Receptor Activation ◽  
Inositol 1,4,5 Trisphosphate ◽  
Trisphosphate Receptor
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