Comparative modeling methods: Application to the family of the mammalian serine proteases

Comparative modeling methods are described that can be used to construct a three-dimensional model structure of a new protein from knowledge of its sequence and of the experimental structures and sequences of other members of its homology family. The methods are illustrated with the mammalian serine protease family, for which seven experimental structures have been reported in the literature, and the sequences for over 35 different protein members of the family are available. The strategy for modeling these proteins is presented, and criteria are developed for determining and assigning the reliability of the modeled structure. Criteria are described that are specially designed to help detect cases in which it is likely that the local structure diverges significantly from the usual conformation of the family.