Our group investigates the functional mechanism of membrane-embedded heterooligomeric macromolecular protein complexes under in vitro and in situ environments. We characterize the structural transitions, conformational equilibria, kinetic and thermodynamic parameters to understand the mechanistic basis of their function. To achieve this goal, we employ a highly interdisciplinary approach involving recombinant membrane protein expression and purification, biochemical/biophysical characterization, and electron spin resonance spectroscopy (ESR) techniques combined with structural modeling.