scaffold generally provide platform for other domain or protein to dock for its efficient function and also provide stability. If the corresponding gene is essential,mutation will be lethal.

Scaffold proteins bring (via interaction domains) two or more other proteins together. Examples would be Kinases being co-recruited to their substrate, etc. Often the scaffold itself is clustering so that it creates a high local concentration of the co-recruited proteins. It's a concept that most often is discussed in the context of protein signalling but also applies to other areas, such as metabolic enzymes.