GDP,”(Guanosine di-phosphate)form of G proteingets promoted and released by Ras GEFswitch 2 traps it inside G protein(concentration in cytosol very low, and G proteins have very low affinity for it, but high affinity for GTP–>why we need GEF)(alpha helical Sos displaces switch 2, allowing it to diffuse away
now need GEF–>GTP bound–>locks G protein in active conformation)”