This project was aimed to the characterization of proteins interacting with the RNA binding proteins PUF1 and PUF3 of Leishmania major (Friedlin strain). For this purpose an immunoprecipitation (IP) strategy was followed. Firstly, protein extracts from L. major promastigotes were incubated with specific antibodies, raised in rabbits, against recombinant proteins PUF1 or PUF3. In parallel, a control IP using a pre-immune serum was performed. After affinity purification of the antibody-protein complexes, proteins were analyzed by Reverse phase- Liquid Chomatography/Mass spectrometry.