DYNAMIC PROPERTIES OF THE GUANINE-NUCLEOTIDE-BINDING PROTEIN ALPHA-SUBUNIT AND COMPARISON OF ITS GUANOSINE TRIPHOSPHATE HYDROLASE DOMAIN WITH THAT OF RAS P21

The dynamic properties of the alpha-subunit of bovine transducin (G al pha(t)) were studied using molecular dynamics simulations and essentia l dynamics analyses. The helical domain of transducin seems to move to ward the guanosine triphosphate hydrolase (GTPase) domain. Our studies suggest that this movement is facilitated by a hinge bending motion t hat is centered on residues GIy56 and Gly179 and that this motion may be involved in GDP release and GTP hydrolysis. The dynamic properties of the GTPase domain of G alpha(t)-GDP were compared to those of ras p 21 and reveal a significant degree of similarity, indicating common dy namic properties for an equivalent domain in two different proteins.