Comparison of frog and human MMP23 with MMP N6. The predicted signal anchor (transmembrane domain) sequences are underlined and the putative furin recognition sequences are in bold. The cysteine residues in the "cysteine-array" unique to MMP23 are in bold and indicated with # below. The amino acid residues characteristic of an Ig (immunoglobulin)-fold are indicated with rectangle boxes below. See Fig. 2 for other information.