"During the last two decades nitric oxide (NO) has emerged as a new chemical messenger in plant biology, which is involved in regulation of many different physiological processes, such as plant defense, transpiration and gas exchange, seed germination, and root development. It is common that many of the biological functions of NO arise as a direct consequence of chemical reactions between proteins and NO or NO oxides. As result of this modification protein activities can be altered, ion channels, transcription factors and signalling proteins can be regulated, the conformation of structural proteins can be altered or proteins can be translocated. Protein translocation is a very important signalling mechanism and there are many reports about protein trafficking during different physiological processes published. However, less is known about NO-dependent protein translocation – especially in the plant field. Based on a proteomics approach we want to investigate the NO-dependent translocation of proteins into the nucleus. Furthermore, a map of nuclear proteins should be generated, which are candidates for protein S-nitrosylation. Besides these proteomic approaches the NPR1/TGA1 system, which is known to be regulated by nitric oxide, will be analysed in more detail. The bZIP transcription factor TGA1 and the regulatory protein NPR1 together are playing a crucial role in SAR during the inducible plant defense response. 3D structures of both proteins will be determined in presence of nitric oxide, to analyse the structural alteration, which result in more effective DNA-binding activity of TGA1. The aim of these studies is to get insight into the regulatory function of NO in gene transcription."