Abstract
Most peroxisomal matrix proteins are synthesized in the cytosol with targeting signal at C (PTS1) or N terminus (PTS2). PTS1 and PTS2 proteins are recognized by recepters, Pex5p and Pex7p, respectively, and carried to peroxisomes, and then imported by the import machinery (Pex10p, Pex12p, etc.) on the peroxisomal membrane. Catalase, an enzyme degrading hydrogen peroxide, is highly accumulated in peroxisomes. Perhaps, there is the specific pathway for catalase because catalase has neither typical PTS1 nor PTS2.
In this study, we analyzed focusing Pex5p, Pex7p, Pex10p and Pex12p. We generated transgenic tobacco BY-2 cells in which they were suppressed by RNAi method. When the expression of Pex5p or Pex7p was suppressed, however, catalase could be imported into peroxisomes. There is a possibility that other proteins besides Pex5p are involved in catalase import. We isolated the proteins binding to tobacco catalase by yeast two-hybrid system, and analyzed the binding proteins.
