Updated project metadata. We study the proteomic profile of endosymbiotic cells (bacteroids) induced by R. leguminosarum bv viciae strain UPM791 in nodules from two different hosts. Comparative analysis of bacteroids induced in pea and lentil nodules revealed the existence of a significant host-specific differential response affecting multiple bacterial proteins, and also revealed the presence of different sets of plant-derived nodule-specific cysteine rich (NCR) peptides.