Structure Based Identification of Protein Family Signatures for Function Annotation

2 Introduction Protein sequences are known to evolve much faster than structures. Pairs of distantly homologous proteins with very low sequence similarity may still share very similar folds and functions. One example of well-preserved structural motifs is given by specific three-dimensional orientations of amino acid residues in the active site of a protein, which are responsible for protein’s biochemical functions. However, most of the time active site residues are hard if not impossible to infer from the primary sequence since the active site residues are frequently quite distant from one another. Developing automated approaches to identifying protein family signatures can be very useful in protein family classification and function annotation.