Abstract
The Obg and Era-like small GTP binding proteins have been found in various prokaryotic and eukaryotic organisms. In bacteria, it has been shown that they participate in a wide range of cellular processes, including signal transduction, cell proliferation, intracellular trafficking and ribosome biogenesis. However, little is known about the biological role of these GTP binding proteins in eukaryotic cells. Intensive search on gene and protein databases revealed that Arabidopsis has ten Obg-Hflx and eight TrmE-Era Superfamily proteins. The sub-cellular localizations of each protein were determined by transient GFP expression assays using protoplasts or culture cells of Arabidopsis. We found that each proteins target to different organelles including chloroplast (eight), mitochondria (three), nucleus (two) and cytoplasm (two). There was two proteins dual-targeting to chloroplast and mitochondria, also one protein dual-targeting to cytoplasm and nucleus. Sub-cellular localization and T-DNA insertional mutant line analysis provide interesting insights for the evolution of these families.
