Gouveia Alexandra M, Guimaraes Carla P, Oliveira Marcia E, Reguenga Carlos, Sa-Miranda Clara, Azevedo Jorge E
Instituto de Biologia Molecular e Celular, Rua do Campo Alegre, 823, 4150-180 Porto, Portugal.
J Biol Chem. 2003 Jan 3;278(1):226-32. doi: 10.1074/jbc.M209498200. Epub 2002 Oct 30.
According to current models of peroxisomal biogenesis, Pex5p cycles between the cytosol and the peroxisome transporting newly synthesized proteins to the organelle matrix. However, little is known regarding the mechanism of this pathway. Here, we show that Pex5p enters and exits the peroxisomal compartment in a process that requires ATP. Insertion of Pex5p into the peroxisomal membrane is blocked by anti-Pex14p IgGs. At the peroxisomal level, two Pex14p-associated populations of Pex5p could be resolved, stage 2 and stage 3 Pex5p, both exposing the majority of their masses into the organelle lumen. Stage 3 Pex5p can be easily detected only under ATP-limiting conditions; in the presence of ATP it leaves the peroxisomal compartment rapidly. Our data suggest that translocation of PTS1-containing proteins across the peroxisomal membrane occurs concomitantly with formation of the Pex5p-Pex14p membrane complex and that this is probably the site from which Pex5p leaves the peroxisomal compartment.
根据目前过氧化物酶体生物发生的模型，Pex5p在细胞质和过氧化物酶体之间循环，将新合成的蛋白质运输到细胞器基质中。然而，关于这条途径的机制却知之甚少。在此，我们表明Pex5p通过一个需要ATP的过程进出过氧化物酶体区室。抗Pex14p IgG可阻断Pex5p插入过氧化物酶体膜。在过氧化物酶体水平上，可以分辨出与Pex14p相关的两个Pex5p群体，即2期和3期Pex5p，它们的大部分质量都暴露在细胞器腔内。3期Pex5p只有在ATP限制条件下才能轻易检测到；在有ATP的情况下，它会迅速离开过氧化物酶体区室。我们的数据表明，含PTS1的蛋白质穿过过氧化物酶体膜的转运与Pex5p-Pex14p膜复合物的形成同时发生，这可能是Pex5p离开过氧化物酶体区室的位点。
