Structures of echistatin (A) and echistatin 1-41 (B). Residues backbones are color-coded as follows: green, hydrophobic; blue, positively charged; red, negatively charged; yellow, containing sulfur; pink/pale blue, hydrophilic; white, tryptophane; magenta, asparagine/glutamine; cyan, glycine/proline. The side chains of the amino acids at the RAR6DD are shown as ball-and-stick models.