Proteins folds, functions and evolution

The evolution of proteins and their functions is reviewed from a structural perspective in the light of the current database. Protein domain families segregate unequally between the three major classes, the 32 different archi tectures and almost 700 folds observed to date. We find that the number of new topologies is still increasing, although 25 new structures are now dete rmined for each new topology. The corresponding analysis and classification of-function is only just beginning, fuelled by the genome data. The struct ural:data revealed unexpected conservations and divergence of function both within and between families. The next five years will see the compilation of a definitive dictionary of protein families and their related functions, based on structural data which reveals relationships hidden at the sequenc e level. Such information will provide the foundation to build a better und erstanding of the molecular basis of biological complexity and: hopefully t o facilitate rational molecular design. (C) 1999 Academic Press.