Abstract: Cell organization and internal movement depends on motor proteins. My lab studies cytoplasmic dynein and its cofactor dynactin. The 2.4MDa dynein/dynactin complex was, until recently, the least understood of all the cytoskeletal motors. Our interest focuses on how a single dynein carries almost all of the minus-end-directed microtubule transport in our cells. It is becoming clear that there is a large family of cargo adaptors that contain long coiled coils and can activate dynein’s long distance movement. We used cryo-electron microscopy (cryoEM) to show how these adaptors recruit dynein to the filament of actin-related protein (Arp1) in dynactin. We revealed how formation of this complex activates dynein. We also discovered that dynactin can recruit two dyneins side-by-side resulting in a faster moving complex. Our future goal is to understand how the core dynein/dynactin/adaptor complexes are recruited to the many cargos that depend on dynein for their transport