Ras proteins participate as a molecular switch in the early steps of the signal transduction
pathway that is associated with cell growth and differentiation. When the protein is in its GTP
complexed form it is active in signal transduction, whereas it is inactive in its GDP
complexed form. A comparison of eight three-dimensional structures of ras proteins in four
different crystal lattices, five with a nonhydrolyzable GTP analog and three with GDP, reveals
that the" on" and" off" states of the switch are distinguished by conformational differences …

Molecular switch for signal transduction : Structural differences between active and inactive
forms of protooncogenic ras proteins | CiNii Research … Molecular switch for signal transduction
: Structural differences between active and inactive forms of protooncogenic ras proteins …