A protein whose main function is to bring other proteins together for them to interact. These proteins usually have many protein binding domains (like WD40 repeats). Below are some experiments that can be done to see if a protein acts as a scaffold in vivo:

• Defined interactions between interacting proteins (yeast 2-hybrid)
• IP (or GST pull downs) scaffold protein. Do other proteins come down with the scaffold?
• Is scaffold protein needed? What happens in a scaffold protein null?
• Use GST fused to different scaffold domains to determine modular organization of scaffold complex.
• Does loss of scaffold protein result in mislocalization of other proteins? (immunofluorescences)
• Does loss of scaffold protein result in instability of target proteins: (immunoblot)
• Does binding one target rely on binding to others? Look at IP in different muant backgrounds.