Biophysical characterization of the Ras protein

Ras is a central switch in regulation of cell proliferation and differentia tion. It becomes activated by extracellular stimuli like growth factors and relays the signal into diverse cellular pathways. A balanced action of reg ulatory proteins is required to maintain the desired level of Ras activity. Oncogenic mutations in Ras lead to uncontrollable over-function, resulting in transformation of the cell. Therefore Ras became a target in many searc hes for anti-cancer agents. From the biochemical point of view Ras serves a s the paradigm of the superfamily of GTP-binding proteins which fulfill cel lular functions as diverse as transmission of vision and regulation of cell morphology. The common theme is switching between the GTP- and GDP-bound f orms which correspond to the active and silent states, respectively This ar ticle describes the function of Ras on the molecular level, leaving the eno rmous wealth of biological data in the Ras field largely aside. Rather, the focus is put on biochemical and biophysical methods which were used to ana lyze the interactions with the diverse partner molecules in a quantitative way to elucidate the mechanism of activation and regulation.