protein trypsinogen from humans. Selecting that entry displays a page that includes the "lineage", which is at the top of most SCOP pages. Human trypsonogen lineage Root: scop Class: All beta proteins [48724] Fold: Trypsin-like serine proteases [50493] barrel, closed; n=6, S=8; greek-key duplication: consists of two domains of the same fold Superfamily: Trypsin-like serine proteases [50494] Family: Eukaryotic proteases [50514] Protein: Trypsin(ogen) [50515] Species: Human (Homo sapiens) [TaxId: 9606] [50519] Searching for "Subtilisin" returns the protein, "Subtilisin from Bacillus subtilis, carlsberg", with the following lineage. Subtilisin from Bacillus subtilis, carlsberg lineage Root: scop Class: Alpha and beta proteins (a/b) [51349] Mainly parallel beta sheets (beta-alpha-beta units) Fold: Subtilisin-like [52742] 3 layers: a/b/a, parallel beta-sheet of 7 strands, order 2314567; left-handed crossover connection between strands 2 & 3 Superfamily: Subtilisin-like [52743] Family: Subtilases [52744] Protein: Subtilisin [52745] Species: Bacillus subtilis, carlsberg [TaxId: 1423] [52746] Although both of these proteins are proteases, they do not even belong to the same fold, which is consistent with them being an example of convergent evolution. Comparison to other classification systems SCOP classification is more dependent on manual decisions than the semi-automatic classification by CATH, its chief rival. Human expertise is used to decide whether certain proteins are evolutionary related and therefore should be assigned to the same superfamily, or their similarity is a result of structural constraints and therefore they belong to the same fold. Another database, FSSP, is purely automatically generated (including regular automatic updates) but offers no classification, allowing the user to draw their own conclusion as to the significance of structural relationships based on the pairwise comparisons of individual protein structures. SCOP successors By 2009, the original SCOP database manually classified 38,000 PDB entries into a strictly hierarchical structure. With the accelerating pace of protein structure publications, the limited automation of classification could not keep up, leading to a non-comprehensive dataset. The Structural Classification of Proteins extended (SCOPe) database was released in 2012 with far greater automation of the same hierarchical system and is full backwards compatible with SCOP version 1.75. In 2014, manual curation was reintroduced into SCOPe to maintain accurate structure assignment. As of February 2015, SCOPe 2.05 classified 71,000 of the 110,000 total PDB entries. SCOP2 prototype was a beta version of Structural classification of proteins and classification system that aimed to more the evolutionary complexity inherent in protein structure evolution. It is therefore not a simple hierarchy,