Table 1.

Summary of proteins, architectures and domain units of eukaryota, bacteria and archaea (RefSeq proteins)

Kingdom	Total proteins	Proteins with Pfam domains	Unique architectures	Domain units
				Single	Double
Eukaryote	1 193 766	750 267	32 737	4764	2435
Bacteria	2 781 568	2 170 351	25 913	4441	2002
Archaea	108 190a	77 785	4399	1301	229

^aDue to the small number of archaic organisms in RefSeq, the total number of archaic proteins is relatively small, compared with those of eukaryote and bacteria. The number of organisms in eukaryote, bacteria and archea in RefSeq is 1470, 1079 and 67, respectively.