We describe how knowledge of three dimensional protein structure can add to the understanding of as yet functionally unannotated protein sequences. Structure determination may reveal that the new protein shares structural similarity with a previously observed structure or that it is a novel fold. The manner in which structure can be used to suggest the function of a protein will depend on the number and diversity of homologous sequences and the extent to which these sequences are functionally characterized. These factors are discussed with reference to a number of illustrative examples of structures solved by structural genomics initiatives.
Keywords: protein, genomics, homologous