Cell Evolution: Gene Transfer Agents and the Origin of Mitochondria Thomas A. Richards, John M. Archibald  Current Biology  Volume 21, Issue 3, Pages R112-R114 (February 2011) DOI: 10.1016/j.cub.2010.12.036 Copyright © 2011 Elsevier Ltd Terms and Conditions

Figure 1 Gene transfer agents (GTAs), α-proteobacterial evolution, and the origin of mitochondria. Schematic shows a hypothetical α-proteobacterial GTA system operating prior to and during the mitochondrial endosymbiosis (events are not necessarily contemporaneous). The ‘host’ is depicted as being a proto-eukaryote with a cytoskeleton, endomembrane system, and phagotrophy, although the hypothesis is equally relevant in the context of alternative models of eukaryogenesis (e.g., those invoking archaeal/bacterial, or archaeal/α-proteobacterial (mitochondrial) symbioses). Possible modes of α-proteobacterial gene transfer as driven by the GTA system are labelled A, B, C, D, and E (see main text). Current Biology 2011 21, R112-R114DOI: (10.1016/j.cub.2010.12.036) Copyright © 2011 Elsevier Ltd Terms and Conditions