AN ABNORMAL KETAMINE RESPONSE IN MUTANTS DEFECTIVE IN THE RYANODINE RECEPTOR GENE RYR-1 (UNC-68) OF CAENORHABDITIS-ELEGANS

To characterize excitation-contraction coupling in Caenorhabditis eleg ans, we applied two approaches. First, we isolated a mutant having abn ormal responses to ketamine, an anesthetic in vertebrates. The novel m utation unc-68(kh30) (isolated as kra-1(kh30)), exhibited strict ketam ine-dependent convulsions followed by paralysis. Second, we cloned the C. elegans ryanodine receptor gene ryr-1 that is located near the cen ter of chromosome V. ryr-1 consists of 46 exons, which encode a predic ted protein of 5071 amino acid residues that is homologous to Drosophi la and vertebrate ryanodine receptors. ryr-1 promoter/lacZ plasmids we re expressed in body-wall and pharyngeal muscles. Non-muscle cell expr ession may be seen with a truncated promoter. In addition, we show tha t the unc-68/kra-1(kh30) mutation is a Ser1444 Asn substitution at a p utative protein kinase C phosphorylation site in ryr-1, and that unc-6 8(e540) contains a splice acceptor mutation that create's a premature stop codon in the ryr-1 gene. We confirmed that unc-68(e540) is a muta tion in ryr-1 by injecting the complete ryr-1 gene into unc-68(e540) a nimals and recovering wildtype progeny. Results presented here will be useful in studying the structure and function of ryanodine receptors in excitation-contraction coupling and in understanding the evolution of ryanodine receptor tissue specificity. (C) 1997 Academic Press Limi ted.