High-affinity [3H]PN200-110 and [3H]ryanodine binding to rabbit and frog skeletal muscle.
In vertebrate skeletal muscle, the voltage-dependent mechanism of sarcoplasmic reticulum (SR) Ca2+ release, commonly referred to as excitation-contraction (E-C) coupling, is mediated by the voltage-sensing dihydropyridine receptor (DHPR), which is believed to affect SR Ca2+ release through a physical interaction with the SR ryanodine receptor (RYR)/Ca2+ release channel. Scatchard analysis of ligand binding of [3H]PN200-110 to the DHPR and [3H]ryanodine to the RYR indicated the presence of high-affinity sites in muscle homogenates, with maximum binding (Bmax) values of 72 +/- 26 and 76 +/- 30 pmol/g wet wt for rabbit skeletal muscle, and 27 +/- 14 and 44 +/- 13 pmol/g wet wt for frog skeletal muscle, respectively. The Bmax values corresponded to a PN200-110-to-ryanodine binding ratio of 0.98 +/- 0.26 and 0.61 +/- 0.24 for rabbit and frog skeletal muscle, respectively, and were found by Student's t test to be significantly different (P < 0.02, n = 7). These results are compared with measurements with isolated rabbit skeletal muscle membrane fractions and discussed in relation to our current understanding of the mechanism of E-C coupling in skeletal muscle.
Anderson
K
K
Department of Biochemistry, University of North Carolina, Chapel Hill 27599-7260.
Cohn
A H
AH
Meissner
G
G
D000818:Animals; D001667:Binding, Competitive; D015220:Calcium Channels / Q000378:metabolism; D020746:Calcium Channels, L-Type; D017275:Isradipine / Q000378:metabolism*; D009124:Muscle Proteins / Q000378:metabolism; D009132:Muscles / Q000378:metabolism*; D011817:Rabbits; D011894:Rana pipiens; D012433:Ryanodine / Q000378:metabolism*; D019837:Ryanodine Receptor Calcium Release Channel; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D014316:Tritium
D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D009124:Muscle Proteins; D019837:Ryanodine Receptor Calcium Release Channel; D014316:Tritium; D012433:Ryanodine; D017275:Isradipine