Most domain families only interact with one or two other families, while a few families are extremely versatile in their interactions and are connected to many families.

Correct Answer: True
The result of the known interactions between members of structural protein families is a graph of connections between families, where the nodes are protein families and the edges represent an interaction between at least one of the domains from each of the two families. This pattern is observed at the level of individual proteins as well, as similar networks can be constructed for the individual proteins in the yeast proteome, for instance.