Cell migration depends on changes in the cell's internal actin cytoskeleton.
These changes are coordinated by molecular switches, called Rho GTPases. The Dbl-family of proteins activates these molecular switches by catalyzing the exchange of GTP for GDP on Rho GTPases. However, these proteins also vary considerably in specificities and activities towards different GTPases, such as Rho, Rac, and Cdc42. I have successfully expressed and purified two protein constructs that contain both a DH and a PH domain. I then used a radioactive GDP release assay to look for differences in catalytic activity, compared to a construct with a DH domain alone.