Analysis of components of the plant TOM complex. A) Phylogenetic tree of the chloroplastic Toc64 and mitochondrial OM64 sequences from plants. Only sequences which showed the characteristic domain structure of Toc64, an N-terminal transmembrane domain followed by an amidase like domain with 3 TPR repeats at the C-terminus, were used for phylogenetic analyses. No such proteins were identified in Ectocarpus siliculosus, Cyanidioschyzon merolae, Chlamydomonas reinhardtii and Chlorella variabilis. For most plant species a clear Toc64 and mtOM64 homologue can be identified however only 1 sequence can be identified in Physcomitrella patens, Selaginella moellendorffii and Picea glauca which all branch closest to the Toc64 chloroplastic proteins. B) Sequence alignment of the Saccharomyces cerevisiae Tom22 with the Arabidopsis thaliana Tom9 and Cyanidioschyzon merloae Tom22. While most plants contain only the Arabidopsis Tom9 like protein Cyanidioscyzon contains a full Tom22 receptor, which shows a high similarity with the yeast Tom22. C) The domain organization of the yeast Tom70, Arabidopsis mtOM64 and an EsTom70 like protein. TM - transmembrane domain and the numbers correspond to the TPR repeats. At - Arabidopsis thaliana, Vv - Vitis vinifera, Gm - Glycine max, Pt - Populus tricocarpa, Os - Oryza sativa, Pp - Physcomitrella patens, Zm - Zea mays, Sc - Saccharomyces cerevisiae, Cm - Cyanidioschyzon merolae, Es - Ectocarpius siliculosus, Sm - Selaginella moellendorffii and Pg - Picea glauca.