help button home button Biophys. J.
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Wagenknecht, T.
Right arrow Articles by Marko, M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Wagenknecht, T.
Right arrow Articles by Marko, M.

Biophys J, November 2002, p. 2491-2501, Vol. 83, No. 5

Electron Tomography of Frozen-Hydrated Isolated Triad Junctions

T. Wagenknecht,*dagger C.-E. Hsieh,* B. K. Rath,* S. Fleischer,Dagger and M. Marko*

 *Wadsworth Center, New York State Department of Health, Empire State Plaza, Albany, New York 12201-0509 USA;  dagger Department of Biomedical Sciences, State University of New York, Empire State Plaza, Albany, New York 12201-0509 USA; and  Dagger Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235 USA

Cryoelectron microscopy and tomography have been applied for the first time to isolated, frozen-hydrated skeletal muscle triad junctions (triads) and terminal cisternae (TC) vesicles derived from sarcoplasmic reticulum. Isolated triads were selected on the basis of their appearance as two spherical TC vesicles attached to opposite sides of a flattened vesicle derived from a transverse tubule (TT). Foot structures (ryanodine receptors) were resolved within the gap between the TC vesicles and TT vesicles, and some residual ordering of the receptors into arrays was apparent. Organized dense layers, apparently containing the calcium-binding protein calsequestrin, were found in the lumen of TC vesicles underlying the foot structures. The lamellar regions did not directly contact the sarcoplasmic reticulum membrane, thereby creating an approx 5-nm-thick zone that potentially constitutes a subcompartment for achieving locally elevated [Ca2+ ] in the immediate vicinity of the Ca2+-conducting ryanodine receptors. The lumen of the TT vesicles contained globular mass densities of unknown origin, some of which form cross-bridges that may be responsible for the flattened appearance of the transverse tubules when viewed in cross-section. The spatial relationships among the TT membrane, ryanodine receptors, and calsequestrin-containing assemblage are revealed under conditions that do not use dehydration, heavy-metal staining, or chemical fixation, thus exemplifying the potential of cryoelectron microscopy and tomography to reveal structural detail of complex subcellular structures.

Biophys J, November 2002, p. 2491-2501, Vol. 83, No. 5
© 2002 by the Biophysical Society   0006-3495/02/11/2491/11  $2.00


This article has been cited by other articles:


Home page
 Biophys. JHome page
G. T. Lines, J. B. Sande, W. E. Louch, H. K. Mork, P. Grottum, and O. M. Sejersted
Contribution of the Na+/Ca2+ Exchanger to Rapid Ca2+ Release in Cardiomyocytes
Biophys. J., August 1, 2006; 91(3): 779 - 792.
[Abstract] [Full Text] [PDF]

Home page
 Biophys. JHome page
N. A. Beard, M. G. Casarotto, L. Wei, M. Varsanyi, D. R. Laver, and A. F. Dulhunty
Regulation of Ryanodine Receptors by Calsequestrin: Effect of High Luminal Ca2+ and Phosphorylation
Biophys. J., May 1, 2005; 88(5): 3444 - 3454.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2002 by the Biophysical Society.