How muscle gene mutation does effect on muscle structure and function of the worm? Mutant animals of the tropomyosin, troponin C genes show Pat (paralyzed, arrested elongation at two fold) phenotypes together with abnormal muscle filament assembly. We present the mutation site of
lev-11 gene was in
tmy-1. We also found that the mutation sites of
unc-68 was in the ryanodine receptor gene
ryr-1. The tropomyosin gene
tmy-1 encodes three tissue specific isoforms and locates on the C. elegans genomic YAC grid near the right end of chromosome I, in the region of the
lev-11 gene. Levamisol is a potent agonist of acetylcholine in the worm and
lev-11 is isolated as twitchers. We determined the sequences of the exon parts of
tmy-1 gene from
lev-11 mutations. The
lev-11(
st557) mutation occurred at the splice donor site of exon 1 and results in translation termination. Although small sized protein from herozygous (+/st557) animal was not detected, our result could be the reason of Pat phenotype of the mutation. The
lev-11(X12) mutation occurred in exon 7 and results in amino acid substitution at 234 from Glu to Lys. This substitution give a charge change from - to + at this point. As this region is common in three isoforms, there may be functional importance of this region for calcium signaling. We have also determined the mutation site of levamisol sensitive but anomalous unc mutation
unc-68 in the ryanodine receptor gene
ryr-1. The ryanodine receptor is a calcium induced calcium channel required for many cellular processes, and its amino acid sequence is similar in mammals and Drosophila. Ryanodine receptor mutations have been identified in malignant hyperthermia in swine and central core disease in humans. Here, we present the structure of and identify mutations in the ryanodine receptor gene
ryr-1 (
unc-68) of the nematode. The
e540 mutation, which causes uncoordinated movement, contains a splice acceptor mutation. The
kh30 mutation, which causes an abnormal response to anesthetic ketamine, has a Ser to Asn substitution at a putative protein kinase C phosphorylation site. Ryr-1 promoter/lacZ plasmids were expressed in body wall and pharyngeal muscles, and in neurons and intestines. These results will allow us to understand the E-C coupling of the worm.