Conserved domains are functional units within a protein that have been used as building blocks in molecular evolution and recombined in various arrangements to make proteins with different functions.
The Conserved Domain Database (CDD) brings together several collections of multiple sequence alignments representing conserved domains, including NCBI-curated domains, which use 3D-structure information to explicitly to define domain boundaries and provide insights into sequence/structure/function relationships, as well as domain models imported from a number of external source databases (Pfam, SMART, COG, PRK, TIGRFAM).
The data are then used for putative functional annotation of protein query sequences based on matches to specific hits (illustrated example) or superfamilies, identification of proteins with similar domain architectures, and protein classification. The Conserved Domains and Protein Classification overview page provides more information about the resources available and how they can be used.
September 13, 2010