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Evidence for the presence of calsequestrin in two structurally different regions of myocardial sarcoplasmic reticulum

Localization of calsequestrin in chicken ventricular muscle cells was determined by indirect immunofluorescence and immuno-Protein A- colloidal gold labeling of cryostat and ultracryotomy sections, respectively. Calsequestrin was localized in the lumen of peripheral junctional sarcoplasmic reticulum...

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Detalles Bibliográficos
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1984
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2113214/
https://www.ncbi.nlm.nih.gov/pubmed/6371026
Descripción
Sumario:Localization of calsequestrin in chicken ventricular muscle cells was determined by indirect immunofluorescence and immuno-Protein A- colloidal gold labeling of cryostat and ultracryotomy sections, respectively. Calsequestrin was localized in the lumen of peripheral junctional sarcoplasmic reticulum, as well as in the lumen of membrane- bound structures present in the central region of the I-band, while being absent from the lumen of the sarcoplasmic reticulum in the A-band region of the cardiac muscle cells. Since chicken ventricular muscle cells lack transverse tubules, the presence of calsequestrin in membrane bound structures in the central region of the I-band suggests that these cells contain nonjunctional regions of sarcoplasmic reticulum that are involved in Ca2+ storage and possibly Ca2+ release. It is likely that the calsequestrin containing structures present throughout the I-band region of the muscle cells correspond to specialized regions of the free sarcoplasmic reticulum in the I-band called corbular sarcoplasmic reticulum. It will be of interest to determine whether Ca2+ storage and possibly Ca2+ release from junctional and nonjunctional regions of the sarcoplasmic reticulum in chicken ventricular muscle cells are regulated by the same or different physiological signals.