Identification of a polymorphic ryanodine receptor gene from Heliothis virescens (Lepidoptera: Noctuidae)

cDNAs encoding the C–terminal 1172 amino acids of a ryanodine receptor (RyR) from the lepidopteran pest Heliothis virescens ( Hv–RyR) have been cloned and characterised. Sequence comparisons, organisational studies on corresponding genomic regions and a genetic segregation analysis provide evidence for two polymorphic alleles of the Hv–RyR locus. Comparison of the Hv–RyR C–terminal amino acid sequence with equivalent regions of other RyRs reveals a high level of overall amino acid homology (74% identity with D. melanogaster and between 47.9 and 50.1% with vertebrate isoforms). Homologies are however not uniformly distributed, though regions of high and low similarity are consistent with patterns in other RyR isoforms. The structural similarity of Hv–RyR with other RyRs is also indicated by comparison of hydropathy profiles and other previously described functional domains. Such results are consistent with this region of Hv–RyR containing the Ca 2+ channel itself and being intimately involved in RyR regulation. Potential uses of the cDNAs described in the discovery and development of novel ryanodine like insecticides are discussed.