Preprotein recognition and translocation by the Toc complex

摘要: Preproptein recognition and translocation across the outer envelope membrane of plastids is catalysed by a proteinaceous machinery, called Toc translocon. The core complex composed pore forming Toc75 two GTP-regulated receptors Toc159 Toc34. A main issue this work nature preprotein transfer apparatus. It still under debate, whether Toc34 or initial receptor. Here, using proteoliposomes with reconstituted either several in vitro binding analysis was shown to act upstream Toc159. Moreover, certain set preproteins engages Toc64 before passing complex. receptor function dynamic association protein are established. central component intermembrane space This migrates at approximately 700 kDa BN-PAGE contains Toc64, Tic22, Toc12 isHsp70. novel identified component, which exposes J-domain toward space. domain recruits isHsp70 translocon an ATP dependent manner. Finally, addresses molecular identity Therefore, purified chromatographic approaches analysed mass spectroscopy. Several peptide masses were obtained, reveal high similarity P. sativum S. oleracea Com70.