Abstract
Most peroxisomal proteins have peroxisomal targeting signal (PTS1, PTS2) present at the C- or N-terminus. The PTS1 and PTS2 are recognized by specific receptors, Pex5p and Pex7p, respectively. The PTS-containing proteins and receptor complex are delivered to peroxisomal membrane and PTS-containing proteins are translocated across the membrane via a translocation apparatus (Pex2p, Pex10p, Pex12p) to the peroxisomal matrix. However, Catalase, major peroxisomal matrix protein, dose not have typical PTS.
In this study, we identified peroxisomal targeting signal of pumpkin catalase (Cat1) by observing the cellular localization of the GFP-Cat1 fusion protein in transgenic tobacco cells and analyzed binding of Pex5p to Cat1 by yeast two-hybrid system. Furthermore, We isolated the cDNAs for tobacco peroxins (Pex5p, Pex7p, Pex12p) and generated transgenic tobacco BY-2 cells lacking these peroxin genes. Then, we analyzed the cellular localization of catalase in these transgenic tobacco cells.
