Fig.1.
A) Spectral tuning of human L and M cone photopigments. A)L-class pigments absorb maximally near 560 nm. B) M-class pigments absorb maximally near 530 nm. C) Genes encoding the L and M opsins each have 6 exons represented by narrow white bars and numbered 1 through 6. The colored regions indicate the exons in the L and M opsin genes. The genes are drawn to scale. Codons that specify amino acids involved in spectral tuning are indicated using the single letter amino acid code and the codon number/amino acid position is indicated by the numbers in the middle of the panel. The single letter amino acid code is as follows: Y = tyrosine, T=threonine, A=alanine, I=isoleucine, S=serine, F=phenylalanine. The magnitude of the spectral shift in nanometers (nm) produced by the indicated amino acid differences specified by each exon are indicated on the far right and far left.