Fig. 7. Dot representation of computer-generated base compositions at three base positions in the codon, which were selected by judging whether imaginary proteins translated under the SNS coding system (S and N mean G or C and either of four bases, respectively) satisfy the six structural conditions (hydropathy, alpha-helix, beta-sheet and beta-turn formabitities, acidic and basic amino acid contents) for appropriate three-dimensional structure formation. Base compositions at the three codon positions were plotted against GC content of the selected genes out of the computer-generated hypothetical genes.