unc-68 encodes a ryanodine receptor involved in regulating C. elegans body-wall muscle contraction.
Striated muscle contraction is elicited by the release of stored calcium ions through ryanodine receptor channels in the sarcoplasmic reticulum. ryr-1 is a C. elegans ryanodine receptor homologue that is expressed in body-wall muscle cells used for locomotion. Using genetic methods, we show that ryr-1 is the previously identified locus unc-68. First, transposon-induced deletions within ryr-1 are alleles of unc-68. Second, transformation of unc-68 mutants with ryr-1 genomic DNA results in rescue of the Unc phenotype. unc-68 mutants move poorly, exhibiting an incomplete flaccid paralysis, yet have normal muscle ultrastructure. The mutants are insensitive to the paralytic effects of ryanodine, and lack detectable ryanodine-binding activity. The Unc-68 phenotype suggests that ryanodine receptors are not essential for excitation-contraction coupling in nematodes, but act to amplify a (calcium) signal that is sufficient for contraction.
Maryon
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Department of Genetics, University of Wisconsin, Madison 53706, USA.
Coronado
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Anderson
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D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000502:physiology*; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002874:Chromosome Mapping; D004251:DNA Transposable Elements / Q000235:genetics; D018509:DNA, Helminth / Q000235:genetics; D017238:Genes, Helminth / Q000235:genetics; D008861:Microsomes / Q000378:metabolism; D008969:Molecular Sequence Data; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D018482:Muscle, Skeletal / Q000648:ultrastructure; D009154:Mutation; D012433:Ryanodine / Q000378:metabolism* / Q000494:pharmacology; D019837:Ryanodine Receptor Calcium Release Channel
D015220:Calcium Channels; D004251:DNA Transposable Elements; D018509:DNA, Helminth; D009124:Muscle Proteins; D019837:Ryanodine Receptor Calcium Release Channel; D012433:Ryanodine