Deduced amino acid sequence and domain organization of human polyserase-3 cDNA. A, the deduced amino acid sequence is shown in single-code letter. The signal peptide is shaded in gray. The two serine-protease domains are underlined. The residues His, Asp and Ser, corresponding to the catalytic triad of the serine protease domains, are indicated with a black dot. B, schematic representation of the domain organization of polyserase-3. The two predicted disulfide bonds around the putative activation site of both serine protease domains are indicated. C, Amino acid sequence alignment around the catalytic serine residues of human polyserase-3 serine protease domains with equivalent sequences deduced from other species. Spd, serine protease domain.Hs, Homo sapiens; Pt, Pan troglodytes, Mm, Mus musculus; Rn, Rattus norvegicus; Bt, Bos taurus; Cf, Canis familiaris.