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The CATH Protein Structure Classification is a semi-automatic, hierarchical classification of protein domains published in 1997 by Christine Orengo, Janet Thornton and their colleagues. CATH shares many broad features with its principal rival, SCOP, however there are also many areas in which the detailed classification differs greatly. ==Hierarchy== The name CATH is an acronym of the four main levels in the classification. CATH defines four classes: mostly-alpha, mostly-beta, alpha and beta, few secondary structures. In order to better understand the CATH classification system it is useful to know how it is constructed: much of the work is done by automatic methods, however there are important manual elements to the classification. The very first step is to separate the proteins into domains. It is difficult to produce an unequivocal definition of a domain and this is one area in which CATH and SCOP differ. The domains are automatically sorted into classes and clustered on the basis of sequence similarities. These groups form the H levels of the classification. The topology level is formed by structural comparisons of the homologous groups. Finally, the Architecture level is assigned manually. Class Level classification is done on the basis of 4 criteria: #Secondary structure content; #Secondary structure contacts; #Secondary structure alternation score; and #Percentage of parallel strands. More detail on this process and the comparison between SCOP, CATH and FSSP can be found in: Hadley & Jones, 1999 and Day ''et al.'', 2003. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「CATH database」の詳細全文を読む スポンサード リンク
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