Figure 1.

(A) Amino acid differences between an OP-susceptible (pLc732) and a diazinon-resistant (pLc7L103) allele of E3. Predicted homologs in the amino acid sequence of Torpedo californica AChE are indicated below, based on a pileup alignment (38) modified to preserve secondary structure elements. (B) Three-dimensional structure of AChE (38) showing the side chains of the amino acids homologous to those that differ in the susceptible and resistant E3 alleles and the active site serine (Ser²⁰⁰) in ball-and-stick format. The rest of the molecule is depicted in ribbon form rendered using molscript (40).