Complex formation between calsequestrin and the ryanodine receptor in fast- and slow-twitch rabbit skeletal muscle.
Linkage between the high-capacity Ca2+-binding protein calsequestrin and the ryanodine receptor is proposed to be essential for proper Ca2+-release during skeletal muscle excitation-contraction coupling. However, no direct biochemical evidence exists showing a connection between these high-molecular-mass complexes in native skeletal muscle membranes. Here, using immunoblot analysis of chemically crosslinked membrane vesicles enriched in triad junctions, we have demonstrated that a very close neighborhood relationship exists between calsequestrin and the ryanodine receptor in both main fiber types. Hence, the luminal Ca2+-reservoir complex appears to be directly coupled to the membrane Ca2+-release complex and oligomerization seems to be of functional importance.
Murray
B E
BE
Department of Pharmacology, University College Dublin, Ireland.
Ohlendieck
K
K
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002155:Calsequestrin / Q000378:metabolism*; D003432:Cross-Linking Reagents; D015151:Immunoblotting; D009119:Muscle Contraction / Q000502:physiology; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism*; D011485:Protein Binding; D016658:Psoas Muscles / Q000378:metabolism; D011817:Rabbits; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism*
D002135:Calcium-Binding Proteins; D002155:Calsequestrin; D003432:Cross-Linking Reagents; D019837:Ryanodine Receptor Calcium Release Channel; D002118:Calcium