Example I (cont.): Quantitative Analysis Reveals the Shape of DNA-PK : Ku Complexes Bound to DNA
In contrast, footprints of DNA-PK bound to DNA in the presence of Ku are larger, indicating that both proteins form a complex in which they are located  adjacently to each other.
Quantitative Analysis of Shapes of Individual Proteins and their Complexes
Effective apparent area (volume/height) provides the “footprint” of a molecule on the surface.
Footprints of unbound and DNA-bound DNA-PK in the samples to which no Ku was added are indistinguishable.
M. Yaneva,T. Kowalewski, M. Lieber EMBO Journal (1997)