Table 1. Elevated sequence conservation in the UTR and CDS regions adjacent to the start and stop codons of eukaryotic mRNAs^a.

	5′-UTRs		5′CDSs		3′CDSs		3′-UTRs
	t	P	t	P	t	P	t	P
Human–mouse (pairwise alignments)	5.923	5.41E–07	5.579	2.4E–06	2.518	0.0085	–5.425	1.88E–06
Rat–mouse (pairwise alignments)	7.999	4.94E–11	3.19	0.0016	2.179	0.0184	–4.032	0.0001
Mammals (multiple alignments)	5.606	1.4E–06	2.329	0.0133	0.704	0.2431	–7.6	1.55E–10
Yeast (multiple alignments)	4.8	1.21E–05	6.975	3.97E–08	4.047	0.0002	–10.327	9.4E–14

^aThe table shows the results of t-test analysis for the 30 nt low conservation region in 3′-UTRs following the stop codon across species, the 30 nt high conservation region in 5′-UTRs immediately upstream of the start codon, and the 30 nt regions of the CDS adjacent to the start or stop codons. In each case, the conservation in the respective 30 nt region was compared with the conservation in the corresponding 70 nt downstream or upstream region. The P-value indicates the probability that the difference in sequence conservation is due to chance.