scholarly journals The network of calcium regulation in muscle.

2003 ◽  
Vol 50 (1) ◽  
pp. 1-30 ◽  
Author(s):  
Anthony N Martonosi ◽  
Slawomir Pikula
Keyword(s):  
Plasma Membranes ◽  
Calcium Release ◽  
Ryanodine Receptors ◽  
Transport Systems ◽  
Molecular Characteristics ◽  
Plasmic Reticulum ◽  
Coordinated Expression ◽  
History Of ◽  
Cardiac Muscles ◽  
And Function

In this review the molecular characteristics and reaction mechanisms of different Ca(2+) transport systems associated with various membranes in muscle cells will be summarized. The following topics will be discussed in detail: a brief history of early observations concerning maintenance and regulation of cellular Ca(2+) homeostasis, characterization of the Ca(2+) pumps residing in plasma membranes and sarco(endo)plasmic reticulum, mitochondrial Ca(2+) transport, Ca(2+)-binding proteins, coordinated expression of Ca(2+) transport systems, a general background of muscle excitation-contraction coupling with emphasis to the calcium release channels of plasma membrane and sarcoplasmic reticulum, the structure and function of dihydropyridine and ryanodine receptors of skeletal and cardiac muscles, and finally their disposition in various types of muscles.

Modulation of type-1 Ins(1,4,5)P3 receptor channels by the FK506-binding protein, FKBP12

2002 ◽  
Vol 361 (2) ◽  
pp. 401-407 ◽  
Author(s):  
Sheila L. DARGAN ◽  
Edward J. A. LEA ◽  
Alan P. DAWSON
Keyword(s):  
Lipid Bilayers ◽  
Calcium Release ◽  
Single Channel ◽  
Binding Protein ◽  
Ryanodine Receptors ◽  
Fk506 Binding Protein ◽  
Single Channel Activity ◽  
And Function ◽  
First Time

FK506-binding protein (FKBP12) is highly expressed in neuronal tissue, where it is proposed to localize calcineurin to intracellular calcium-release channels, ryanodine receptors and Ins(1,4,5)P3 receptors (InsP3Rs). The effects of FKBP12 on ryanodine receptors have been well characterized but the nature and function of binding of FKBP12 to InsP3R is more controversial, with evidence for and against a tight interaction between these two proteins. To investigate this, we incorporated purified type-1 InsP3R from rat cerebellum into planar lipid bilayers to monitor the effects of exogenous recombinant FKBP12 on single-channel activity, using K+ as the current carrier. Here we report for the first time that FKBP12 causes a substantial change in single-channel properties of the type-1 InsP3R, specifically to increase the amount of time the channel spends in a fully open state. In the presence of ATP, FKBP12 can also induce co-ordinated gating with neighbouring receptors. The effects of FKBP12 were reversed by FK506. We also present data showing that rapamycin, at sub-optimal concentrations of Ins(2,4,5)P3, decreases the rate of calcium release from cerebellar microsomes. These results provide evidence for a direct functional interaction between FKBP12 and the type-1 InsP3R.

scholarly journals Ryanodine Receptors: Structure, Expression, Molecular Details, and Function in Calcium Release

2010 ◽  
Vol 2 (11) ◽  
pp. a003996-a003996 ◽  
Author(s):  
J. T. Lanner ◽  
D. K. Georgiou ◽  
A. D. Joshi ◽  
S. L. Hamilton
Keyword(s):  
Calcium Release ◽  
Ryanodine Receptors ◽  
And Function

Expression and functional characterization of SCaMPER: a sphingolipid-modulated calcium channel of cardiomyocytes

2003 ◽  
Vol 284 (3) ◽  
pp. C780-C790 ◽  
Author(s):  
Amy L. Cavalli ◽  
Nicole W. O'Brien ◽  
Steven B. Barlow ◽  
Romeo Betto ◽  
Christopher C. Glembotski ◽  
...  
Keyword(s):  
Calcium Channel ◽  
Calcium Release ◽  
Cardiac Tissue ◽  
Ryanodine Receptors ◽  
Functional Characterization ◽  
Substantial Reduction ◽  
Pcr Cloning ◽  
Cellular Events ◽  
T Tubules ◽  
And Function

Calcium channels are important in a variety of cellular events including muscle contraction, signaling, proliferation, and apoptosis. Sphingolipids have been recognized as mediators of intracellular calcium release through their actions on a calcium channel, sphingolipid calcium release-mediating protein of the endoplasmic reticulum (SCaMPER). The current study investigates the expression and function of SCaMPER in cardiomyocytes. Northern analyses and RT-PCR cloning and sequencing revealed SCaMPER expression in both human and rat cardiac tissue. Immunofluorescence and Western blot analyses demonstrated that SCaMPER is abundant in cardiac tissue and is localized to the sarcotubular junction. This was confirmed by the colocalization of SCaMPER with dihydropyridine and ryanodine receptors by confocal microscopy. Purified T tubules were shown to contain SCaMPER and immunoelectron micrographs suggested that SCaMPER is located to the junctional T tubules, but a junctional SR localization cannot be ruled out. The sphingolipid ligand for SCaMPER, sphingosylphosphorylcholine (SPC), initiated calcium release from the cardiomyocyte SR. Importantly, antisense knockdown of SCaMPER mRNA produced a substantial reduction of sphingolipid-induced calcium release, suggesting that SCaMPER is a potentially important calcium channel of cardiomyocytes.

scholarly journals Calcium Release Channels: Structure and Function of IP3 Receptors and Ryanodine Receptors

2021 ◽  
Author(s):  
Kellie A Woll ◽  
Filip Van Petegem
Keyword(s):  
Small Molecules ◽  
Calcium Release ◽  
Current Knowledge ◽  
Ryanodine Receptors ◽  
Ip3 Receptors ◽  
Electron Microscopic ◽  
Channel Opening ◽  
And Function ◽  
Opening And Closing ◽  
Common Architecture

Ca2+-release channels are giant membrane proteins that control the release of Ca2+ from the endoplasmic and sarcoplasmic reticulum. The two members, ryanodine receptors (RyRs) and inositol-1,4,5-trisphosphate Receptors (IP3Rs), are evolutionarily related and are both activated by cytosolic Ca2+. They share a common architecture, but RyRs have evolved additional modules in the cytosolic region. Their massive size allows for the regulation by tens of proteins and small molecules, which can affect the opening and closing of the channels. In addition to Ca2+, other major triggers include IP3 for the IP3Rs, and depolarization of the plasma membrane for a particular RyR subtype. Their size has made them popular targets for study via electron microscopic methods, with current structures culminating near 3Å. The available structures have provided many new mechanistic insights int the binding of auxiliary proteins and small molecules, how these can regulate channel opening, and the mechanisms of disease-associated mutations. They also help scrutinize previously proposed binding sites, as some of these are now incompatible with the structures. Many questions remain around the structural effects of post-translational modifications, additional binding partners, and the higher-order complexes these channels can make in situ. This review summarizes our current knowledge about the structures of Ca2+-release channels and how this informs on their function.

Structure and Function of Renal Organic Cation Transporters

Physiology ◽  
1998 ◽  
Vol 13 (1) ◽  
pp. 11-16 ◽  
Author(s):  
Hermann Koepsell ◽  
Andreas Busch ◽  
Valentin Gorboulev ◽  
Petra Arndt
Keyword(s):  
Plasma Membranes ◽  
Organic Cation ◽  
Structure And Function ◽  
Transport Systems ◽  
Organic Cations ◽  
Renal Tubules ◽  
Organic Cation Transporters ◽  
Cation Transporters ◽  
And Function

Polyspecific transport systems in the kidney mediate the excretion and reabsorption of organic cations. Electrogenic import systems and electroneutral export systems in the basolateral and luminal plasma membranes of proximal renal tubules are involved. Two subtypes of electrogenic import systems have been cloned from rats and humans and functionally characterized.

Structure and function of the neuronal endomembrane system

1993 ◽  
Vol 51 ◽  
pp. 98-99
Author(s):  
Maryann E. Martone ◽  
Victoria M. Simpliciano ◽  
Ying Zhang ◽  
Thomas J. Deerinck ◽  
Mark H. Ellisman
Keyword(s):  
Intracellular Calcium ◽  
Calcium Release ◽  
Smooth Endoplasmic Reticulum ◽  
Ryanodine Receptors ◽  
Cell Types ◽  
Calcium Stores ◽  
Endomembrane System ◽  
Ip3 Receptor ◽  
And Function ◽  
Cerebellar Purkinje Neurons

Components of the endomembrane system in a variety of cell types appear to function in the storage and release of calcium similar to the muscle sarcoplasmic reticulum. Many proteins involved in intracellular calcium regulation in skeletal or smooth muscle, e.g. Ca++ ATPase, calsequestrin, the inositol l,4,5,trisphosphate (TP3) receptor and the ryanodine binding protein, are found in the nervous system where they are particularly abundant within the smooth endoplasmic reticulum (SER) of cerebellar Purkinje neurons. Immunolocalization studies suggest, however, that calcium regulatory proteins are not uniformly distributed within the SER but are concentrated in or excluded from certain domains. For example, the IP3 and ryanodine receptors, two distinct calcium channels which mediate calcium release by different ligands, are found associated with the SER in cell bodies and dendrites of chick cerebellum but only the IP3 receptor is found within dendritic spines. These results are consistent with evidence that cells may possess multiple intracellular calcium stores that are pharmacologically, spatially and perhaps physically distinct.

scholarly journals Thapsigargin-sensitive Ca2+-ATPases account for Ca2+ uptake to inositol 1,4,5-trisphosphate-sensitive and caffeine-sensitive Ca2+ stores in adrenal chromaffin cells

1995 ◽  
Vol 307 (3) ◽  
pp. 749-758 ◽  
Author(s):  
J C J Poulsen ◽  
C Caspersen ◽  
D Mathiasen ◽  
J M East ◽  
R E A Tunwell ◽  
...  
Keyword(s):  
Adrenal Medulla ◽  
Chromaffin Cells ◽  
Plasma Membranes ◽  
Ryanodine Receptors ◽  
Strongly Correlated ◽  
Adrenal Chromaffin Cells ◽  
Distribution Profile ◽  
Plasmic Reticulum ◽  
Inositol 1,4,5 Trisphosphate ◽  
Adrenal Chromaffin

In chromaffin cells of adrenal medulla, heterogeneity of Ca2+ stores has been suggested with respect to the mechanisms of Ca2+ uptake and release. We have examined Ca(2+)-ATPases responsible for loading of Ca2+ stores in these cells for their sensitivity to thapsigargin, a highly selective inhibitor of the SERCA [sarco(endo)plasmic reticulum calcium ATPase] family of intracellular Ca2+ pumps. Using immunostaining, we studied the distribution of Ca(2+)-ATPases, and of receptors for inositol 1,4,5-trisphosphate (InsP3) and ryanodine, in the density-gradient fractions of microsomes from bovine adrenal medulla. In parallel, we examined distribution profiles of ATP-dependent Ca2+ uptake in the same fractions, along with subcellular markers for plasma membranes and endoplasmic reticulum (ER). Two Ca(2+)-ATPase-like proteins (116 and 100 kDa) were detected, consistent with the presence of SERCA 2b and SERCA 3 isoenzymes of Ca2+ pumps. The distribution of these putative Ca(2+)-ATPase iso-enzymes paralleled that of InsP3 and ryanodine receptors. This distribution of ER Ca(2+)-ATPases, as determined immunologically, was consistent with that of thapsigargin-sensitive, but not of thapsigargin-insensitive, ATP-dependent Ca2+ uptake. In contrast, the distribution profile of the thapsigargin-insensitive Ca2+ uptake was strongly correlated to that of plasma membranes, and co-distributed with plasma membrane Ca(2+)-ATPase detected immunologically. In isolated, permeabilized chromaffin cells, InsP3 and caffeine induced Ca2+ release following an ATP-dependent Ca2+ accumulation to the stores. This accumulation was abolished by thapsigargin. Together, these data strongly indicate that the thapsigargin-sensitive, presumably SERCA-type Ca(2+)-ATPases account for Ca2+ uptake to InsP3-sensitive, as well as to caffeine-sensitive, Ca2+ stores in bovine adrenal chromaffin cells.

Kedudukan dan Fungsi Bahasa dalam Permuseuman

Metahumaniora ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 54
Author(s):  
Erlina Zulkifli Mahmud ◽  
Taufik Ampera ◽  
Yuyu Yohana Risagarniwa ◽  
Inu Isnaeni Sidiq
Keyword(s):  
Human Life ◽  
Field Research ◽  
Communicative Function ◽  
Language Functions ◽  
The Past ◽  
Library Research ◽  
History Of ◽  
And Function ◽  
Museum Guides ◽  
Bahasa Indonesia

Kedudukan dan fungsi bahasa sebagai alat komunikasi manusia mencakup seluruh bidang kehidupan termasuk ilmu pengetahuan antara lain terkait sejarah peradaban manusia; bagaimana manusia mempertahankan hidupnya, bagaimana manusia memperlakukan alam, bagaimana alam menyediakan segala kebutuhan manusia. Apa yang dilakukan manusia saat ini, saat lampau, dan apa yang dilakukan manusia jauh di masa prasejarah, bagaimana kondisi alam di masa-masa tersebut, apa perubahan dan perkembangannya, dapat didokumentasikan melalui bahasa, divisualisasikan kembali, lalu dipajang sebagai salah satu upaya konversai dan preservasi dalam satu institusi yang disebut museum. Penelitian ini membahas kedudukan dan fungsi bahasa dalam permuseuman. Bagaimana kedudukan dan fungsi bahasa dalam permuseuman baik dalam informasi yang disampaikan oleh pemandu wisata museumnya maupun yang terpajang menyertai benda-benda dan gambar-gambar merupakan tujuan dari penelitian ini. Metode penelitian yang digunakan adalah gabungan antara metode lapangan dan metode literatur. Hasil penelitian menunjukkan bahwa secara umum kedudukan bahasa Indonesia berada pada urutan pertama setelah Bahasa Inggris dan keberadaan kedua bahasa dalam permuseuman ini melibatkan dua fungsi utama bahasa, yakni fungsi komunikatif dan fungsi informatif.The existence and function of language  as a medium of communication covers all fields of human life including knowledge, one of them is the history of human civilization; how humans survived, how human utilized nature for their lives, and how nature provides all the necessities for humans. What humans have been doing now, what they have done in the past and far before that in the pre-history time, how the conditions of the nature at those times were and what changes as well as progresses occurred are documented using language, then re-visualized,  displayed as one of conservation and preservation acts in an institution called museum. This research discusess the existence and function of language in museums. How important the existence of a language in museums and what language functions used in museums both in informations given by the museum guides and on the displays accompanying objects and pictures are the aims of this research. The methods used are the combination between field research and library research. The results show that generally the existence of Indonesian language plays more important role than English and both languages have two main functions; communicative function and informative function.     

John among the Apocalypses

2020 ◽  
Author(s):  
Benjamin E. Reynolds
Keyword(s):  
Gospel Of John ◽  
Central Place ◽  
Reception History ◽  
Genre Theory ◽  
Synoptic Gospels ◽  
Book Of Revelation ◽  
Distinctive Features ◽  
History Of ◽  
Definition Of ◽  
And Function

The central place of revelation in the Gospel of John and the Gospel’s revelatory telling of the life of Jesus are distinctive features of John when compared with the Synoptic Gospels; yet, when John is compared among the apocalypses, these same features indicate John’s striking affinity with the genre of apocalypse. By paying attention to modern genre theory and making an extensive comparison with the standard definition of “apocalypse,” the Gospel of John reflects similarities with Jewish apocalypses in form, content, and function. Even though the Gospel of John reflects similarities with the genre of apocalypse, John is not an apocalypse, but in genre theory terms, John may be described as a gospel in kind and an apocalypse in mode. John’s narrative of Jesus’s life has been qualified and shaped by the genre of apocalypse, such that it may be called an “apocalyptic” gospel. Understanding the Fourth Gospel as “apocalyptic” Gospel provides an explanation for John’s appeal to Israel’s Scriptures and Mosaic authority. Possible historical reasons for the revelatory narration of Jesus’s life in the Gospel of John may be explained by the Gospel’s relationship with the book of Revelation and the history of reception concerning their writing. An examination of Byzantine iconographic traditions highlights how reception history may offer a possible explanation for reading John as “apocalyptic” Gospel.

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