... signal(promoter) but no targeting sequence (transit peptide), andit thus ends up expressing a cytosolic protein (one that thuscannot compete in the organelle with the organelle-encodedprotein). ... been transferred from organelle genomes to thenucleus during the course of evolution [19,20,84].Thus, one might expect all of the proteins of thetricarboxylic acid cycle to re¯ect an a-proteobacterialorigin, ... However, the eukaryotes sampledhere seem, in most cases, all to possess the same acquiredgene. Thus, if these kinds of acquisition involved donor(s)that were not the ancestor of mitochondria,...