Amino acid similarity among mouse (m) and human (h) ADAM33 proteins, and Xenopus laevis (X) ADAM13. Residues identical to the mouse protein are indicated in bold. Putative signal sequence cleavage sites (SS) are indicated by arrow. The metalloprotease site (MP), disintegrin loop (DL) and transmembrane domain (TM) are boxed and cysteine residues are highlighted by black boxes. The metalloprotease (MPD), disintegrin-like (DD), cysteine-rich (CRD), and EGF-like (EGF) domains are indicated.