Figure 1.

Cleavage site sequence logo showing specificity for caspase-3. Amino acids preferred in positions P4–P4′ are shown in single-letter code. The specificity is shown as a string where each position is separated by a forward slash character and multiple letters in a position indicate a wide specificity for these amino acids. The scissile bond is shown by a red cross symbol. In the diagram, the height of the letter is proportional to the number of cleavage sites in which it is present. Positions P4–P4′ are numbered one to eight, with the scissile bond between residues four and five. Caspase-3, like most caspases, has a preference for Asp in P1 and a majority of substrates also have Asp in P4.