This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. ABSTRACT: The aim is to reconstruct the specific association between two calcium channels in skeletal muscle (the L type calcium channel of DHPR of the surface membrane/T tubules) and the calcium release channel of the SR. This can be done by tomography of the SR/T tubule junctions in an intact muscle fiber, and requires specific instrumentation available at the Albany Resource: A high pressure rapid freezing apparatus, an ultramicrotome for frozen sections, and intermediate high voltage cryo-electron microscope with high tilt angle.