This volume provides in depth reviews of the  protein targeting translocation  processes, gene transfer processes and genome reduction processes in the host and  in the endosymbiont  which were likely utilized  during the evolution of an endosymbiont into  mitochondria, mitochondria related organelles, simple and complex  chloroplasts. These  reviews cover both the current understanding of the host processes as well as the  evolutionary outcomes used by these organelles  for protein targeting and translocation.  Reviews of the current knowledge of these topics are plentiful but scattered throughout the bacterial, parasite, plant and animal literature; here, reviews of  current knowledge with evolutionary outcomes and future perspectives, written by  leading researchers in their respective areas,  are united into one comprehensive volume, essential for students and scientists interested in or working onsubcellular protein localization, protein targeting signals, translocation of proteins across and insertion into membranes, nucleic acid transfer between genomes, genome reduction and evolution of mitochondria and chloroplast.