The goal of our research is to understand protein biogenesis, the production of functional proteins by the cellular machinery. A number of molecular machines work together in this process: The ribosome puts together the building blocks to form long protein chains, "translating" the genetic information. Molecular chaperones help the "folding" of these protein chains into specific shapes that are necessary for protein function. Many essential proteins, including antibodies and hormones such as insulin, must then cross cell boundaries to reach their cellular destination. This "translocation" is powered by molecular motors within our cells that somehow push or pull the relatively large protein through the cellular membrane without accidentally allowing other small molecules to slip in or out at the same time. We are using laser tweezers, a tool to tug and pull on single molecules, to watch proteins being synthesized, folded, and translocated. At the same time, we measure the forces involved in these processes, such as the forces required to move a protein across a cellular membrane. Direct observation of individual molecules at work has proven to be extremely powerful for investigating how they operate. Because so many essential cell functions hinge on the smooth operation of the protein biogenesis machinery—and flaws in the process have been linked to disorders such as neurodegeneration, cancer and diabetes—our findings could lead to novel treatments for restoring central cellular activities.