Table 4.

Distribution of functional classes in bacterial and archaeal 'translation operons'

	Function	Total	High frequency	Low frequency
Distribution of functional classes in bacterial 'translation operons'
No	F3	1.57	0	2.94
	H	0.79	0	1.47
	I	0.79	0	1.47
	I2	1.57	0	2.94
	J	5.51	5.08	5.88
	J1	1.57	3.39	0
	J3	0.79	0	1.47
	J4	3.15	5.08	1.47
	K2	1.57	0	2.94
	L	0.79	0	1.47
	L1	0.79	0	1.47
	M	1.57	0	2.94
	N	0.79	0	1.47
	P	1.57	0	2.94
	R	2.36	0	4.41
	S	2.36	0	4.41
	D	0.79	0	1.47
Yes	E	0.79	0	1.47
	H3	0.79	0	1.47
	H5	0.79	0	1.47
	I	1.57	0	2.94
	J	0.79	0	1.47
	J1	1.57	1.69	1.47
	J3	1.57	3.39	0
	J4	5.51	10.17	1.47
	L1	0.79	0	1.47
	N	1.57	0	2.94
	R	2.36	0	4.41
	S	0.79	0	1.47
Yes*	E9	0.79	0	1.47
	F5	0.79	0	1.47
	I1	0.79	0	1.47
	J	1.57	0	2.94
	J1	2.36	0	4.41
	J2	2.36	0	4.41
	J3	1.57	1.69	1.47
	J4	3.15	5.08	1.47
	K1	1.57	0	2.94
	K2	0.79	1.69	0
	L1	0.79	0	1.47
	N	1.57	1.69	1.47
	O	0.79	0	1.47
	R	1.57	0	2.94
Yes**	F1	0.79	0	1.47
	F3	0.79	0	1.47
	J	0.79	0	1.47
	J1	2.36	3.39	1.47
	J3	11.81	25.42	0
	J4	14.96	30.51	1.47
	K1	0.79	1.69	0
Distribution of functional classes in archaeal 'translation operons'
No	E	0.88	0	2.78
	EM	0.88	0	2.78
	F	0.88	1.28	0
	F3	0.88	1.28	0
	G2	0.88	0	2.78
	J	3.51	0	11.11
	K1	0.88	1.28	0
	K2	0.88	1.28	0
	L	0.88	0	2.78
	R	0.88	0	2.78
	S	3.51	5.13	0
	T	0.88	0	2.78
Yes	J	0.88	0	2.78
	J1	0.88	0	2.78
	O	0.88	0	2.78
	R	0.88	0	2.78
	S	3.51	1.28	8.33
Yes*	C	0.88	0	2.78
	E2	0.88	0	2.78
	F	0.88	0	2.78
	F5	0.88	0	2.78
	J	1.75	1.28	2.78
	J1	2.63	2.56	2.78
	K	0.88	1.28	0
	K1	2.63	3.85	0
	K2	0.88	1.28	0
	L	0.88	0	2.78
	N	1.75	1.28	2.78
	O	0.88	0	2.78
Yes**	G2	0.88	1.28	0
	J	4.39	0	13.89
	J1	1.75	2.56	0
	J3	19.3	26.92	2.78
	J4	31.58	41.03	11.11
	K1	3.51	5.13	0

The list of functions is divided into blocks according to the presence or absence of a yeast homolog in the microarray data with the same coding as in Figure3. The last three columns represent the percentage of genes in each functional category with respect to all the genes in the 'operon' (Total), those genes found only in more than (High frequency) or less than 50% (Low frequency) of all the species studied. Functions found with high frequency in different organisms are highlighted in bold. It can be seen that the COG functional categories of the yeast, bacterial and archaeal genes are very similar, suggesting also that proteins with the same function, but not necessarily evolutionarily related, could replace each other in different organisms. More comprehensive tables of the data summarized in Tables 1,2,3,4 are provided as additional data files.