A cell adhesion protein from the crayfish Pacifastacus leniusculus, a serine proteinase homologue similar to Drosophila masquerade

A cDNA encoding a protein resembling masquerade, a serine proteinase homolo gue expressed during embryogenesis, larval, and pupal development in Drosop hila melanogaster, mas identified in hemocytes of the adult freshwater cray fish, Pacifastacus leniusculus. The crayfish protein is similar to Drosophi la masquerade in the following aspects: (a) overall sequence of the serine proteinase domain, such as the position of three putative disulfide bridges , glycine in the place of the catalytic serine residue, and the presence of a substrate-lining pocket typical for trypsins; (b) the presence of severa l copies of a disulfide-knotted motif in the putative propeptide, This masq uerade-like protein is cleaved into a 27-kDa fragment, which could be detec ted by immunoblot analysis using an affinity-purified antibody against a sy nthetic peptide in the C-terminal domain of the protein. The 27-kDa protein could be immunoaffinity-purified from hemocyte lysate supernatant and exhi bited cell adhesion activity in vitro, indicating that the C-terminal domai n of the crayfish masquerade-like protein mediates cell adhesion.