High molecular weight proteins in the nematode C. elegans bind [3H]ryanodine and form a large conductance channel.
Single-channel properties of a polypeptide fraction from the nematode Caenorhabditis elegans highly enriched in binding sites were studied in planar bilayers. [3H]Ryanodine binding sites were purified by sucrose gradient centrifugation of C. elegans microsomes solubilized in CHAPS detergent. The highest [3H]ryanodine binding activity sedimented at approximately 18% sucrose (wt/vol), and was composed of a major polypeptide with a M(r) of 360,000 and a minor polypeptide with a M(r) of 170,000. The ryanodine-binding polypeptide(s) formed a Ca(2+)-permeable channel with a permeability ratio P(divalent)/P(monovalent) = 4 and two conductance states of 215 pS and 78 pS in 0.25 M KCl. Ryanodine locked the channel in the 78 pS state and inhibited transitions between the 215 pS and 78 pS states. These data demonstrated the presence of a ryanodine receptor in C. elegans with functional properties comparable to those described in mammalian muscle.
Kim
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YK
Department of Physiology, School of Medicine, University of Wisconsin, Madison 53706.
Valdivia
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HH
Maryon
E B
EB
Anderson
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P
Coronado
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R
D000818:Animals; D001665:Binding Sites; D055592:Biophysical Phenomena; D001703:Biophysics; D017173:Caenorhabditis elegans / Q000378:metabolism*; D015220:Calcium Channels / Q000737:chemistry / Q000378:metabolism*; D015801:Helminth Proteins / Q000737:chemistry / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D008970:Molecular Weight; D009124:Muscle Proteins / Q000737:chemistry / Q000378:metabolism; D011950:Receptors, Cholinergic / Q000737:chemistry / Q000378:metabolism; D012433:Ryanodine / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel
D015220:Calcium Channels; D015801:Helminth Proteins; D009124:Muscle Proteins; D011950:Receptors, Cholinergic; D019837:Ryanodine Receptor Calcium Release Channel; D012433:Ryanodine