The sarcoplasmic reticulum Ca2+-ATPase, SERCA1a, contains endoplasmic reticulum targeting information

Cyclic ADP-ribose (cADPR), an endogenous metabolite of beta-NAD+, activates Ca2+ release from endoplasmic reticulum in sea urchin eggs via the ryanodine receptor (RyR) pathway. A similar role has been proposed in cardiac sarcoplasmic reticulum (SR), although this remains controversial. We therefore investigated the ability of cADPR to induce Ca2+ release from canine cardiac SR microsomes using fluo 3 to monitor extravesicular Ca2+ concentration. We found that cADPR induced Ca2+ release in a concentration-dependent manner, whereas neither its precursor, NAD+, nor its metabolite, ADP-ribose, elicited a consistent effect. In addition, an additive effect on calcium release between cADPR and 9-Me-7-Br-eudistomin-D (MBED), an activator of RyR, was found as well as no cross-desensitization between cADPR and MBED. Specific blockers of the RyR did not abolish the cADPR-induced Ca2+ release. These results provide evidence for cADPR-induced Ca2+ release from dog cardiac SR via a novel mechanism which is independent of RyR activation.

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THE SARCOPLASMIC RETICULUM IN MUSCLE CELLS OF AMBLYSTOMA LARVAE

The Journal of Cell Biology ◽

10.1083/jcb.2.4.163 ◽

1956 ◽

Vol 2 (4) ◽

pp. 163-170 ◽

Cited By ~ 58

Author(s):

Keith R. Porter

Keyword(s):

Electron Microscopy ◽

Endoplasmic Reticulum ◽

Sarcoplasmic Reticulum ◽

Constant Width ◽

Muscle Cells ◽

Cell Types ◽

Thin Sections ◽

System A ◽

Structural Relationships ◽

Complex Membrane

Electron microscopy of thin sections of muscle fibers in myotomes of Amblystoma larvae has revealed the presence of a complex, membrane-limited system of canaliculi and vesicles which form a lace-like reticulum around and among the myofibrils. This seems to correspond to the sarcoplasmic reticulum of the earlier light microscopists and the endoplasmic reticulum of other cell types. The elements constituting the reticulum are disposed in a pattern which bears a constant relation to the bands of the adjacent myofibrils and is therefore repeated in each sarcomere. At the H band the system is transversely continuous but not so at other levels. Longitudinally continuity is interrupted at the Z bands where large vesicles belonging to adjacent sarcomere segments of the system face off on opposite sides of the band. The opposing faces of these vesicles are flat and separated by a space of more or less constant width, in which are located small, finger-shaped vesicles. In view of these and other close structural relationships with the myofibrils it seems appropriate to assign to the system a role in the conduction of the excitatory impulse.

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Endoplasmic reticulum targeting tumour selective photocytotoxic oxovanadium(iv) complexes having vitamin-B6 and acridinyl moieties

Dalton Transactions ◽

10.1039/c5dt03412d ◽

2016 ◽

Vol 45 (2) ◽

pp. 783-796 ◽

Cited By ~ 19

Author(s):

Samya Banerjee ◽

Akanksha Dixit ◽

Anjali A. Karande ◽

Akhil R. Chakravarty

Keyword(s):

Endoplasmic Reticulum ◽

Schiff Base ◽

Visible Light ◽

Vitamin B6 ◽

Schiff Base Complexes ◽

Endoplasmic Reticulum Targeting ◽

Tumor Selective

Vitamin-B6 Schiff base complexes of oxovanadium(iv) having (acridinyl)dipyridophenazine show tumor selective visible light-induced photocytotoxicity by endoplasmic reticulum targeting1O2-mediated apoptosis.

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Development of a multifunctional luciferase reporters system for assessing endoplasmic reticulum-targeting photosensitive compounds

Cell Stress and Chaperones ◽

10.1007/s12192-014-0517-4 ◽

2014 ◽

Vol 19 (6) ◽

pp. 927-937 ◽

Cited By ~ 10

Author(s):

Shengchao Lin ◽

Lingling Zhang ◽

Kecheng Lei ◽

Anle Zhang ◽

Ping Liu ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Endoplasmic Reticulum Targeting ◽

Luciferase Reporters

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Tunneling cell processes in myocytes of stretched mouse atria

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1987.253.2.h432 ◽

1987 ◽

Vol 253 (2) ◽

pp. H432-H443

Author(s):

E. Page ◽

G. E. Goings ◽

B. Power ◽

J. Upshaw-Earley

Keyword(s):

Endoplasmic Reticulum ◽

Sarcoplasmic Reticulum ◽

Ionic Composition ◽

Interstitial Space ◽

Cytoplasmic Matrix ◽

Cytoplasmic Structure ◽

Section Electron ◽

Cell Processes ◽

Peptide Secretion

Serial section electron micrographs of mouse atria stretched in vitro show that myocytes have cell processes which tunnel into adjacent myocytes for 8 microns or more. The tunneling cell processes (TCP) (diam 4–6.2 microns) lack myofibrils and organelles associated with atrial peptide secretion. The glycogen-rich TCP cytoplasmic matrix contains conspicuous tubules and vesicles originating from endoplasmic reticulum and resembling free sarcoplasmic reticulum (SR). TCP are surrounded by a plasmalemma derived from their myocyte of origin, the plasmalemma of the tunneled myocyte, and an intervening narrow compartment continuous with the interstitial space. Profiles having the characteristics cytoplasmic structure of TCP are also found both in the interstitial space between myocytes and near the longitudinal terminations where myocyte ends about on the interstitial space. We suggest that TCP tubules and vesicles may proliferate and/or transport in response to stretch, might be free SR, and may respond to stretch-activated changes in ionic composition or potential of the surrounding myocyte and narrow intercellular compartment.

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