Our laboratory focuses in single molecule manipulation of biomolecules. This area is a new field of research and allows studying the effect of the forces on the structure of proteins and the concomitant changes in their function. It also permits to determine the forces and torques developed in the course of the mechanochemical conversion in molecular motors. Inside the cell, mechanical forces are produced in molecular processes as diverse as transcription, replication, translation, chromosomal segregation, protein unfolding, translocation of proteins across the membranes and cellular movement. Now, our work is focused in determining the importance of the force associated to the domain movements of BiP (immunoglobulin heavy-chain binding protein) protein during protein translocation in the ER, also focusing in the kinetic properties of BiP and in the conformational changes that occur during its ATPase cycle, as it is working in the translocation process. However, it’s still not clear the specific mechanism that BiP uses to perform its work during translocation.This is the reason of the great importance of a detailed study at the single molecule level which will provide information about this important mechanism. One aim is to determine the mechanochemical mechanism that BiP uses working in the translocation. To do this, we are focusing primarily on the study of individual molecules, with optical tweezers, and an innovative combination of magnetic tweezers with TIRF (Total Internal Fluorescence Reflection) using single molecule FRET (Förster Resonance Energy Transfer) dyes.