scholarly journals Ultrastructural localization of calsequestrin in rat skeletal muscle by immunoferritin labeling of ultrathin frozen sections.

1983 ◽  
Vol 97 (5) ◽  
pp. 1573-1581 ◽  
Author(s):  
A O Jorgensen ◽  
A C Shen ◽  
K P Campbell ◽  
D H MacLennan
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Central Region ◽  
Ultrastructural Localization ◽  
Frozen Sections ◽  
Rat Skeletal Muscle ◽  
Major Site ◽  
Ultrathin Frozen Sections ◽  
Terminal Cisternae

The ultrastructural localization of calsequestrin in rat skeletal muscle (gracilis) was determined by indirect immunoferritin labeling of ultrathin frozen sections. Calsequestrin was found in the lumen of transversely and longitudinally oriented terminal cisternae but was absent from most of the longitudinal sarcotubules and the fenestrated sarcoplasmic reticulum. Calsequestrin was occasionally observed in vesicular structures found in the central region of the I band. Since calsequestrin is believed to provide the major site of Ca2+ sequestration in the sarcoplasmic reticulum, the present results support the view that Ca2+, transported to the lumen of the sarcoplasmic reticulum, is preferentially sequestered in the terminal cisternae, but they also suggest that additional Ca2+ sequestration may occur near the center of the I band.

scholarly journals Ultrastructural localization of the Ca2+ + Mg2+-dependent ATPase of sarcoplasmic reticulum in rat skeletal muscle by immunoferritin labeling of ultrathin frozen sections.

1982 ◽  
Vol 92 (2) ◽  
pp. 409-416 ◽  
Author(s):  
A O Jorgensen ◽  
A C Shen ◽  
D H MacLennan ◽  
K T Tokuyasu
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Plasma Membranes ◽  
Ultrastructural Localization ◽  
Published Data ◽  
Frozen Sections ◽  
Dependent Atpase ◽  
Sarcoplasmic Reticulum Membrane ◽  
Ultrathin Frozen Sections ◽  
Terminal Cisternae ◽  
Simultaneous Visualization

The ultrastructural localization of the Ca2+ + Mg2+-dependent ATPase of sarcoplasmic reticulum in rat gracilis muscle was determined by indirect immunoferritin labeling of ultrathin frozen sections. Simultaneous visualization of ferritin particles and of adsorption-stained cellular membranes showed that the Ca2+ + Mg2+-ATPase was concentrated in the longitudinal sarcoplasmic reticulum and in the nonjunctional regions of the terminal cisternae membrane but was virtually absent from mitochondria, plasma membranes, transverse tubules, and junctional sarcoplasmic reticulum. Ferritin particles were found preponderantly on the cytoplasmic surface of the membrane, in agreement with published data showing an asymmetry of the Ca2+ + Mg2+-ATPase within the sarcoplasmic reticulum membrane. Comparison of the density of ferritin particles in fast and slow myofibers suggested that the density of the Ca2+ + Mg2+-ATPase in the sarcoplasmic reticulum membrane in a fast myofiber is approximately two times higher than in a slow myofiber.

scholarly journals Ultrastructural localization of calsequestrin in adult rat atrial and ventricular muscle cells.

1985 ◽  
Vol 101 (1) ◽  
pp. 257-268 ◽  
Author(s):  
A O Jorgensen ◽  
A C Shen ◽  
K P Campbell
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Ultrastructural Localization ◽  
Major Site ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Adult Rat ◽  
Dependent Atpase ◽  
Sarcoplasmic Reticulum Membrane ◽  
Structural Differences ◽  
Ultrathin Frozen Sections ◽  
Junctional Sarcoplasmic Reticulum

The distribution of calsequestrin in rat atrial and ventricular myocardial cells was determined by indirect immunocolloidal gold labeling of ultrathin frozen sections. The results presented show that calsequestrin is confined to the sarcoplasmic reticulum where it is localized in the lumen of the peripheral and the interior junctional sarcoplasmic reticulum as well as in the lumen of the corbular sarcoplasmic reticulum, but absent from the lumen of the network sarcoplasmic reticulum. Comparison of these results with our previous studies on the distribution of the Ca2+ + Mg2+-dependent ATPase of the cardiac sarcoplasmic reticulum show directly that the Ca2+ + Mg2+-dependent ATPase and calsequestrin are confined to distinct regions within the continuous sarcoplasmic reticulum membrane. Assuming that calsequestrin provides the major site of Ca2+ sequestration in the lumen of the sarcoplasmic reticulum, the results presented support the idea that both junctional (interior and peripheral) and specialized nonjunctional (corbular) regions of the sarcoplasmic reticulum are involved in Ca2+ storage and possibly release. Furthermore, the structural differences between the junctional and the corbular sarcoplasmic reticulum support the possibility that Ca2+ storage and/or release from the lumen of the junctional and the corbular sarcoplasmic reticulum are regulated by different physiological signals.

scholarly journals Calsequestrin: a well-known but curious protein in skeletal muscle

2020 ◽  
Vol 52 (12) ◽  
pp. 1908-1925
Author(s):  
Jin Seok Woo ◽  
Seung Yeon Jeong ◽  
Ji Hee Park ◽  
Jun Hee Choi ◽  
Eun Hui Lee
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Human Skeletal Muscle ◽  
Rabbit Skeletal Muscle ◽  
Muscle Type ◽  
Muscle Diseases ◽  
The Past ◽  
Muscle Tissues ◽  
Suitable Amount ◽  
Terminal Cisternae

AbstractCalsequestrin (CASQ) was discovered in rabbit skeletal muscle tissues in 1971 and has been considered simply a passive Ca2+-buffering protein in the sarcoplasmic reticulum (SR) that provides Ca2+ ions for various Ca2+ signals. For the past three decades, physiologists, biochemists, and structural biologists have examined the roles of the skeletal muscle type of CASQ (CASQ1) in skeletal muscle and revealed that CASQ1 has various important functions as (1) a major Ca2+-buffering protein to maintain the SR with a suitable amount of Ca2+ at each moment, (2) a dynamic Ca2+ sensor in the SR that regulates Ca2+ release from the SR to the cytosol, (3) a structural regulator for the proper formation of terminal cisternae, (4) a reverse-directional regulator of extracellular Ca2+ entries, and (5) a cause of human skeletal muscle diseases. This review is focused on understanding these functions of CASQ1 in the physiological or pathophysiological status of skeletal muscle.

Ca2+ Uptake Coupled to Glycogen Phosphorolysis in the Glycogenolytic-Sarcoplasmic Reticulum Complex from Rat Skeletal Muscle

1996 ◽  
Vol 51 (7-8) ◽  
pp. 591-598 ◽  
Author(s):  
M. Nogues ◽  
A. Cuenda ◽  
F. Henao ◽  
C. Gutiérrez-Merino
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Glycogen Phosphorylase ◽  
Rat Skeletal Muscle ◽  
Subcellular Structure ◽  
Sequential Action ◽  
Physiological Conditions ◽  
Low Concentrations ◽  
Ischemic Muscle ◽  
Stimulation Of

Abstract The glycogenolytic-sarcoplasmic reticulum complex from rat skeletal muscle accumulates Ca2+ upon stimulation of glycogen phosphorolysis in the absence of added ATP. It is shown that an efficient Ca2+ uptake involves the sequential action of glycogen phosphorylase, phosphoglucomutase and hexokinase, which generate low concentrations of ATP (approximately 1 -2 μм) compartmentalized in the immediate vicinity of the sarcoplasmic reticulum Ca2+, Mg2+-ATPase (the Ca2+ pump). The Ca2+ uptake supported by glycogenolysis in this subcellular structure is strongly stimulated by micromolar concentrations of AMP, showing that the glycogen phosphorylase associated with this complex is in the dephosphorylated b form. The results point out that the flux through this compartmentalized metabolic pathway should be enhanced in physiological conditions leading to increased AMP concentrations in the sarcoplasm, such as long-lasting contractions and in ischemic muscle.

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