Cooper's work shows that some repair pathways pick and choose from a common toolbox of protein components, Johnson notes. The switching of one machine into another, or the modification of one machine into another is one of the great things that cells are able to do. XPD also shares the dual role of DNA repair and transcription factor, notes Kraemer. They may represent a link between repair and transcription, but we don't know exactly how it's working. So you can see how that capacity of the helicase can be important in transcription and repair.
Cooper notes that the events that initiate repair remain the most difficult to understand.
We're trying to see how the structure of the DNA damage and the structure of the enzyme control repair. Commonalities in the structures of several repair enzymes that have been characterized through X-ray crystallography may play a role. He suspects that they all recognize an extra helical flip. We're beginning to envision how the initiating steps may be coordinated. Cooper and Tainer agree that signal transduction may provide an initiating event.