Fig. 2. GP42 TGase homologs containing the surface-exposed Pep-13 motif are highly conserved among the genus Phytophthora. (A) RT–PCR demonstrated the presence of GP42 TGase-related transcripts in Phytophthora species (upper panel). Immunoblot analysis of culture filtrates (50 µg protein/lane) using anti-Pep13 antibodies revealed that each species possessed a GP42-like protein containing the Pep-13 motif (middle panel). In-gel TGase assays demonstrated that the GP42-related proteins possessed TGase activity (lower panel). Purified P.sojae GP42 (100 ng) was used as a positive control for both immunodetection and TGase activity (lane GP42). (B) The alignment of the deduced amino acid sequences of the RT–PCR products highlights the conservation of the Pep-13 motif (boxed). The asterisk marks the position of the sole N-glycosylation site of the P.sojae GP42. (C) The hydropathy plot based on the Eisenberg algorithm (Eisenberg et al., 1984) predicts the Pep-13 motif to reside in a hydrophilic region of the protein.