CATH protein domain database

The CATH protein domain database (http //www.biochem.ucl.ac.uk/bsm/cath) is a hierarchical classification of protein domain structures into evolutionary families and structural groupings depending on sequence and structure similarity (Pearl et al, 2000). The protein domains are classified according to four major levels. 

In order to make as much data on the structure and its determination available in the databases, approaches for automated data harvesting are being developed. Structure classification schemes, as implemented for example in the SCOP, CATH, andFSSP databases, elucidate the relationship between protein folds and function and shed light on the evolution of protein domains. 

Protein-pattern databases cover both motifs or functional domains and secondary structure. We have included the entire InterPro family of databases, as well as BLOCKS, CDD, and a description of patterns found in Swiss-Prot sequences. DSSP, ISSD, PSSD, and CATH are covered in the secondary-structure section. 

All current structural classification methods are based on the same scheme Protein structures are first divided into discrete, globular domains, which are then classified at the levels of (1) class, (2) folds, (3) superfa-milies, and (4) families. The differences among existing schemes come from the methods that define the domains and the procedures that classify. After reviewing the terms that define a classification, the three main protein structure classifications available, SCOP, CATH, and the DALI Domain Dictionary (DDD), will be described. Links to these databases and related services are listed in Table 7. 

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