An updated view of the structural basis for dihydropyridine receptors-ryanodine receptors direct molecular interaction in skeletal muscle.

This presentation reviews images of electron micrographs from various skeletal muscles identifying a consistent association of diydropyridine receptors (DHPR) tetrads with  alternate ryanodine receptors. Imaging of the junctional gap in triads from various sources  provide direct evidence for the  association of four diydropyridine receptors (DHPRs), clustered into tetrads, with alternate ryanodine receptors (RyRs). It is not clear whether firing of all four components of a tetrad is necessary to fully activate the opening of the RyR channel.