TABLE 3.

Distribution of W3110 ORFs and identified absent ORFs by functional classes

Categorya	No. of ORFs	No. of ORFs absent	% of absent ORFs
Amino acid metabolism	136	32	23.5
Biosynthesis of cofactors, pros- thetic groups, and carriers	127	11	8.7
Cell envelope	195	73	37.4
Cellular process	105	27	25.7
Central intermediary metabolism	154	57	37.0
Energy metabolism	368	130	35.3
Fatty acid and phospholipid metabolism	60	7	11.7
Nucleotide metabolism	117	16	13.7
Regulatory functions	107	29	27.1
Replication	90	12	13.3
Transport and binding protein	369	131	35.5
Translation	152	7	4.6
Transcription	48	8	16.7
Other categories	338	97	28.7
Hypothetical	2,024	787	38.9
Total	4,390	1,424	32.4

^aFunctional categories of W3110 ORFs were based on information from the GanoBase 4.0 database (http://ecoli.aist-nara.ac.jp/gb4/search/function/orffunc.php).