Class, Architecture, Topology CATH protein domain

CATH is a protein structure classification in which protein domains are clustered at four major levels class (C), architecture (A), topology (T), and homologous superfamily (H), each of which are described below. CATH uses a semiautomatic classification procedure that filters out nonprotein, models, and Coj-only structures from the PDB. Only crystal structures solved to resolution better than 3.0 A are considered, together with all NMR structures. The latest update of CATH, v2.5.1, was released January 28, 2004 and includes 48,391 domains. 

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