In pursuit of ryanodine receptors gating in the plasma membrane of RINm5F pancreatic β-cells

Sitsapesan, Rebecca

doi:10.4161/isl.1.1.9055

Cited by 4 publications

(4 citation statements)

References 33 publications

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“…However, the reported currents do not mimic any earlier reported currents of RyRs (156;157). It has been suggested that the channels described by Rosker et al, may represent a novel, non-selective ion-channel (158). In our study, the Ca 2+ entry was blocked by SKF 96365, a compound that does not block RyRs.…”

Section: Ryrs Operate Activation Of Trp-like Channelssupporting

confidence: 56%

ADP ribose is an endogenous ligand for the purinergic P2Y1 receptor

Gustafsson

Muraro

Dahlberg

et al. 2011

Molecular and Cellular Endocrinology

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Section: Ryrs Operate Activation Of Trp-like Channelssupporting

confidence: 56%

ADP ribose is an endogenous ligand for the purinergic P2Y1 receptor

Gustafsson

Muraro

Dahlberg

et al. 2011

Molecular and Cellular Endocrinology

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“…There seem, although the estimate is only approximate, to be ∼10 of these channels per cell. We ( 185 ) and others ( 172 ) have noted that neither γ of these channels nor the effects of high concentrations of ryanodine on γ faithfully replicate the exhaustively studied behavior of RyR in lipid bilayers. RyR in bilayers typically have γ values for K + , Na + , and Cs + that are 3−4-fold larger than those observed in our recordings from the PM ( 185 ) (practical difficulties have prevented us from measuring γ values for bivalent cations of the PM channels), and ryanodine usually locks RyR into a subconducting state ( 190 ).…”

Section: Functional Ryanodine Receptors In the Plasma Membranementioning

confidence: 80%

“…In chromaffin cells, both RyR and IP 3 R appear to escape the ER and function as Ca 2+ release channels within secretory vesicles ( 118 ). Perhaps more contentious is the possibility that RyR may be expressed in the PM ( 172 ). In this section, we briefly review the evidence that RyR are functionally expressed in the PM of some cells, and in the concluding section, we consider the possible physiological significance of RyR and IP 3 R in the PM.…”

Section: Functional Ryanodine Receptors In the Plasma Membranementioning

confidence: 99%

“…In cardiac myocytes, too, caffeine or an increased cytosolic Ca 2+ concentration stimulated opening of cation channels with high conductance (γ Na ∼ 400 pS) and permeability to Ba 2+ 188 , 189 . The most persuasive evidence that these might be RyR in the PM is the ability of ryanodine, as it does for RyR in bilayers ( 172 , 177 ), to lock the channels into a subconducting state ( 189 ). Collectively, these observations provide persuasive evidence that cardiac myocytes may express just one to four functional RyR within the PM ( 189 ).…”

Section: Functional Ryanodine Receptors In the Plasma Membranementioning

confidence: 99%

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Ca²⁺ Channels on the Move

2009

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The versatility of Ca2+ as an intracellular messenger derives largely from the spatial organization of cytosolic Ca2+ signals, most of which are generated by regulated openings of Ca2+-permeable channels. Most Ca2+ channels are expressed in the plasma membrane (PM). Others, including the almost ubiquitous inositol 1,4,5-trisphosphate receptors (IP3R) and their relatives, the ryanodine receptors (RyR), are predominantly expressed in membranes of the sarcoplasmic or endoplasmic reticulum (ER). Targeting of these channels to appropriate destinations underpins their ability to generate spatially organized Ca2+ signals. All Ca2+ channels begin life in the cytosol, and the vast majority are then functionally assembled in the ER, where they may either remain or be dispatched to other membranes. Here, by means of selective examples, we review two issues related to this trafficking of Ca2+ channels via the ER. How do cells avoid wayward activity of Ca2+ channels in transit as they pass from the ER via other membranes to their final destination? How and why do some cells express small numbers of the archetypal intracellular Ca2+ channels, IP3R and RyR, in the PM?

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Calcium Signaling in the Islets

Islam

2010

Advances in Experimental Medicine and Biology

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Easy access to rodent islets and insulinoma cells and the ease of measuring Ca(2+) by fluorescent indicators have resulted in an overflow of data that have clarified minute details of Ca(2+) signaling in the rodent islets. Our understanding of the mechanisms and the roles of Ca(2+) signaling in the human islets, under physiological conditions, has been hugely influenced by uncritical extrapolation of the rodent data obtained under suboptimal experimental conditions. More recently, electrophysiological and Ca(2+) studies have elucidated the ion channel repertoire relevant for Ca(2+) signaling in the human islets and have examined their relative importance. Many new channels belonging to the transient receptor potential (TRP) family are present in the beta-cells. Ryanodine receptors, nicotinic acid adenine dinucleotide phosphate channel, and Ca(2+)-induced Ca(2+) release add new dimension to the complexity of Ca(2+) signaling in the human beta-cells. A lot more needs to be learnt about the roles of these new channels and CICR, not because that will be easy but because that will be difficult. Much de-learning will also be needed. Human beta-cells do not have a resting state in the normal human body even under physiological fasting conditions. Their membrane potential under physiologically relevant resting conditions is approximately -50 mV. Biphasic insulin secretion is an experimental epiphenomenon unrelated to the physiological pulsatile insulin secretion into the portal vein in the human body. Human islets show a wide variety of electrical activities and patterns of [Ca(2+)](i) changes, whose roles in mediating pulsatile secretion of insulin into the portal vein remain questionable. Future studies will hopefully be directed toward a better understanding of Ca(2+) signaling in the human islets in the context of the pathogenesis and treatment of human diabetes.

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In pursuit of ryanodine receptors gating in the plasma membrane of RINm5F pancreatic β-cells

Cited by 4 publications

References 33 publications

ADP ribose is an endogenous ligand for the purinergic P2Y1 receptor

ADP ribose is an endogenous ligand for the purinergic P2Y1 receptor

Ca²⁺ Channels on the Move

Calcium Signaling in the Islets

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In pursuit of ryanodine receptors gating in the plasma membrane of RINm5F pancreatic β-cells

Cited by 4 publications

References 33 publications

ADP ribose is an endogenous ligand for the purinergic P2Y1 receptor

ADP ribose is an endogenous ligand for the purinergic P2Y1 receptor

Ca2+ Channels on the Move

Calcium Signaling in the Islets

Contact Info

Product

Resources

About

Ca²⁺ Channels on the Move