Protein structure taxonomy based

SCOP, CATH, and DDD agree on most of their classifications, despite differences in the classification methods they have implemented, and in the rules of protein structure and taxonomy they are based on. Hadley and Jones were the first to publish a detailed comparison of the fold classifications produced by SCOP, CATH, and FSSP. They showed that the three classification systems tend to agree in most cases, and that the discrepancies and inconsistencies are accounted for by a small number of problems. Among these, the domain assignment plays a crucial role. As mentioned, the separation of proteins into domains is a difficult and often subjective process. Many... 

Taking all factors into account, NCBI uses four core data elements bibliographic citations, DNA sequences, protein sequences, and three-dimensional structures. In addition, two projects (taxonomy and genome maps) are more interpretive but nonetheless are so important as organizing and linking resources that NCBI has built a considerable base in these areas as well. 

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