Highly cooperative and hysteretic response of the skeletal muscle ryanodine receptor to changes in proton concentrations.
Ryanodine receptors are key molecules in excitation-contraction coupling of skeletal muscle. They form the pore of the calcium release channel, which is regulated by Ca and ATP. Multiple proton titration sites are involved in controlling the different open states of the channel, as indicated by the following: i) the channel had a biphasic response to changes in proton concentrations around neutral pH; ii) the activities of the channel were inhibited by acidic pHs in a highly cooperative manner; and iii) the channel exhibited pronounced hysteresis to changes in pH. Four distinct conductance states can be identified in the single ryanodine-activated calcium release channel. The distribution of the multiple conductance states depends on the level of [Ca], ATP, and pH in the recording solution. The data are consistent with the multimeric structure of the skeletal muscle ryanodine receptor.
Ma
J
J
Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106.
Zhao
J
J
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D004553:Electric Conductivity; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects; D009124:Muscle Proteins / Q000187:drug effects / Q000502:physiology*; D009132:Muscles / Q000502:physiology*; D011817:Rabbits; D019837:Ryanodine Receptor Calcium Release Channel; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors
D015220:Calcium Channels; D009124:Muscle Proteins; D019837:Ryanodine Receptor Calcium Release Channel; D000255:Adenosine Triphosphate; D002118:Calcium