BRITE functional hierarchies

Orthologs and modules
00001  KEGG Orthology (KO)
00003  KEGG reaction modules

Protein families: metabolism
01000  Enzymes
01001  Protein kinases
01009  Protein phosphatases and associated proteins
01002  Peptidases and inhibitors
01003  Glycosyltransferases
01005  Lipopolysaccharide biosynthesis proteins
01011  Peptidoglycan biosynthesis and degradation proteins
01004  Lipid biosynthesis proteins
01008  Polyketide biosynthesis proteins
01006  Prenyltransferases
01007  Amino acid related enzymes
00199  Cytochrome P450
00194  Photosynthesis proteins

Protein families: genetic information processing
03000  Transcription factors
03021  Transcription machinery
03019  Messenger RNA biogenesis
03041  Spliceosome
03011  Ribosome
03009  Ribosome biogenesis
03016  Transfer RNA biogenesis
03012  Translation factors
03110  Chaperones and folding catalysts
04131  Membrane trafficking
04121  Ubiquitin system
03051  Proteasome
03032  DNA replication proteins
03036  Chromosome and associated proteins
03400  DNA repair and recombination proteins
03029  Mitochondrial biogenesis

Protein families: signaling and cellular processes
02000  Transporters
02044  Secretion system
02042  Bacterial toxins
02022  Two-component system
02035  Bacterial motility proteins
03037  Cilium and associated proteins
04812  Cytoskeleton proteins
04147  Exosome
02048  Prokaryotic defense system
04030  G protein-coupled receptors
04050  Cytokine receptors
04054  Pattern recognition receptors
03310  Nuclear receptors
04040  Ion channels
04031  GTP-binding proteins
04052  Cytokines and neuropeptides
04515  Cell adhesion molecules
04090  CD molecules
01504  Antimicrobial resistance genes
00535  Proteoglycans
00536  Glycosaminoglycan binding proteins
00537  Glycosylphosphatidylinositol (GPI)-anchored proteins
04091  Lectins
04990  Domain-containing proteins not elsewhere classified

Viral protein families
03200  Viral proteins
03210  Viral fusion proteins

RNA family
03100  Non-coding RNAs