eggNOG is a database of nested orthologous gene groups (NOGs) infered using unsupervised clustering applied to >2,000 complete genomes followed by comprehensive characterization and analysis of the resulting gene families. eggNOG provides orthologous group assignments at >100 different taxonomic levels as well as multiple sequence alignments, maximum-likelihood trees and broad functional annotations for each group accessible via a web interface or through bulk download.
Huerta-Cepas et al. eggNOG 4.5: a hierarchical orthology framework with improved functional annotations for eukaryotic, prokaryotic and viral sequences. Nucleic Acids Res. D1. 2016. PMID: 26582926
Powell et al. eggNOG v4.0: nested orthology inference across 3686 organisms. Nucleic Acids Res. Database issue. 2014. PMID: 24297252
Powell et al. eggNOG v3.0: orthologous groups covering 1133 organisms at 41 different taxonomic ranges. Nucleic Acids Res. Database issue. 2012. PMID: 22096231
Muller et al. eggNOG v2.0: extending the evolutionary genealogy of genes with enhanced non-supervised orthologous groups, species and functional annotations. Nucleic Acids Res. Database issue. 2010. PMID: 19900971
Jensen et al. eggNOG: automated construction and annotation of orthologous groups of genes. Nucleic Acids Res. Database issue. 2008. PMID: 17942413