Formation of junctions involved in excitation-contraction coupling in skeletal and cardiac muscle.
During excitation-contraction (e-c) coupling of striated muscle, depolarization of the surface membrane is converted into Ca2+ release from internal stores. This process occurs at intracellular junctions characterized by a specialized composition and structural organization of membrane proteins. The coordinated arrangement of the two key junctional components--the dihydropyridine receptor (DHPR) in the surface membrane and the ryanodine receptor (RyR) in the sarcoplasmic reticulum--is essential for their normal, tissue-specific function in e-c coupling. The mechanisms involved in the formation of the junctions and a potential participation of DHPRs and RyRs in this process have been subject of intensive studies over the past 5 years. In this review we discuss recent advances in understanding the organization of these molecules in skeletal and cardiac muscle, as well as their concurrent and independent assembly during development of normal and mutant muscle. From this information we derive a model for the assembly of the junctions and the establishment of the precise structural relationship between DHPRs and RyRs that underlies their interaction in e-c coupling.
Flucher
B E
BE
Department of Biochemical Pharmacology, University of Innsbruck, Austria.
Franzini-Armstrong
C
C
D000818:Animals; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000502:physiology*; D020746:Calcium Channels, L-Type; D002462:Cell Membrane / Q000502:physiology; D006321:Heart / Q000502:physiology*; D007425:Intracellular Membranes / Q000502:physiology; D008954:Models, Biological; D009119:Muscle Contraction; D009124:Muscle Proteins / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D009200:Myocardial Contraction; D019837:Ryanodine Receptor Calcium Release Channel; D012519:Sarcoplasmic Reticulum / Q000502:physiology; D015398:Signal Transduction
D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D009124:Muscle Proteins; D019837:Ryanodine Receptor Calcium Release Channel; D002118:Calcium