Sequence optimization of the hACHE-S gene. Shown are the native (cDNA) human gene sequence (upper) and the optimized gene (lower). Nucleotide changes are shown, whereas unmodified nucleotides are represented by dashes. Above the two compared DNA sequences is the predicted amino-acid sequence of the AChE-S protein. Underline: potential methylation sites. Yellow box: infrequent plant codons. Red box: potential 5'-intron splice sites. Blue box: potential downstream 3'-intron splice sites. Purple box: a potential polyadenylation positional element. Please note that the only amino-acid deviations from the human cDNA are an R2A change in the human sequence and insertion of a G residue on this position in the plant-optimized sequence. These changes were introduced to facilitate cloning into the plant expression vectors used in this study.