TABLE 1.

KEGG database contents and identifiers

Category	Database	Content	KEGG identifier	Expanded prefix
Systems information	PATHWAY	KEGG pathway maps	map number	<org>, ko/ec/rn
	BRITE	BRITE hierarchies and tables	br/ko number	<org>
	MODULE	KEGG modules Reaction modules	M number RM number	<org>_M
Genomic information	KO	KO groups for functional orthologs	K number
	GENES	Genes and proteins	<org>:<entry>
	GENOME	KEGG organisms and viruses	T number, gn:<org>
Chemical information	COMPOUND	Small molecules	C number
	GLYCAN	Glycans	G number
	REACTION	Biochemical reactions	R number
	RCLASS	Reaction class	RC number
	ENZYME	Enzyme nomenclature	Ec:<entry>
Health information	NETWORK	Network variation maps Disease‐related network elements	nt number N number
	VARIANT	Human gene variants	hsa_var:<entry>
	DISEASE	Human diseases	H number
	DRUG	Drugs	D number
	DGROUP	Drug groups	DG number

Abbreviations: <org>, KEGG organism code such as hsa for Homo sapiens; <entry>, entry identifier.