image: Crosslinking analyses revealed that the trimeric mature TOM complex dynamically exchanges with a dimeric Tom22-free form that provides an assembly platform for the integration of new subunits. The fully functional trimeric TOM complex consists of the channel protein Tom40, tethering multifunctional subunit Tom22, and small subunits Tom5, Tom6, and Tom7, together with the receptor subunits Tom20 and Tom70, which are not shown in the figure. This study revealed that this trimeric complex exchanges with the Tom40 dimeric complex lacking the tethering subunit Tom22. The dimeric complex can function as a platform or template to incorporate a newly synthesized and imported Tom40 protein, and then to assemble into the mature trimeric TOM complex. By doing so, the TOM complex could remove the defective Tom40 molecule and replace it with a new functional Tom40 molecule, to maintain the full function of the TOM complex. This material relates to a paper that appeared in the Sept. 25, 2015 issue of Science, published by AAAS. The paper, by T. Shiota at Monash University in Melboune, VIC, Australia, and colleagues was titled, "Molecular architecture of the active mitochondrial protein gate." view more
Credit: Toshiya Endo and Kentaro Imai