GlnR is the global regulator of nitrogen assimilation in Streptomyces coelicolor M145 and other actinobacteria. Two-dimensional polyacrylamide gel electrophoresis analyses were performed to identify new GlnR target genes by proteomic comparison of wild-type S. coelicolor M145 and a Delta glnR mutant. Fifty proteins were found to be differentially regulated between S. coelicolor M145 and the Delta glnR mutant. These spots were identified by nanoHPLC-ESI-MS/MS and classified according to their cellular role. Most of the identified proteins are involved in amino acid biosynthesis and in carbon metabolism, demonstrating that the role of GlnR is not restricted to nitrogen metabolism. Thus, GlnR is supposed to play an important role in the global metabolic control of S. coelicolor M145.