TABLE 2.

DNA methylation of individual 5′-CG-3′ dinucleotides in the p3–p4 segment of the IAPI DNA region^a

5′-CG-3′ position	% Methylation in cell line:
	BHK21	T637	BHK21-λ7	BHK21-λ10
1	39.8	77.3	42.6	47.2
2	51.8	82.4	72.0	70.1
3	54.8	81.6	65.3	65.7
4	46.6	70.3	51.0	66.7
5	79.6	88.9	86.5	83.3
6b	65.2	90.4	76.9	76.9
7	73.0	90.0	79.6	83.8
8	65.4	86.1	78.8	77.5
9c	67.9	85.1	67.3	85.5
10	67.9	86.8	64.3	64.3
11c	87.5	93.3	84.9	87.9
12b	48.6	67.1	39.2	56.5
13	66.0	83.1	62.5	78.1
14	72.1	94.7	64.3	82.4
15	67.6	83.3	57.7	77.9
16	68.4	76.7	57.7	77.5
17	51.0	75.0	52.0	52.3
18	48.6	58.0	35.8	47.1
20	42.0	79.5	66.0	62.0
21	27.8	61.5	41.1	53.4
22	37.8	70.1	43.6	37.3
28	44.1	69.2	43.9	35.8
29	35.0	54.5	35.2	34.3
30	60.0	92.9	60.7	52.5
31	50.9	77.8	77.4	45.5
32	73.5	83.6	80.8	73.5
33b	58.9	77.6	82.1	72.6
34	65.2	86.3	82.1	76.5

^aFor details, see the legend to Fig. 7 and Results. The values are the averages of methylated 5′-CG-3′ dinucleotides in the DNAs from 123 DNA clones of BHK21 cells (reference cell line), 79 DNA clones of T637 cells, 58 DNA clones of BHK21-λ7 cells, and 73 DNA clones of BHK-λ10 cells. For all of these clones, the DNA sequence was determined after the genomic DNA had been treated with bisulfite, the p3–p4 segment had been amplified by PCR, and individual PCR products had been molecularly cloned in the pGEM-T vector (Promega). In our BHK21 cells, 5′-CG-3′ dinucleotide positions 23 to 27 were frequently deleted compared to the published sequence (25), and positions 19 and 35 were altered to non-5′-CG-3′ (TG) dinucleotides. Those sequences were therefore not included in the analyses. 

^bHhaI (5′-GCGC-3′) sites. 

^cHpaII (5′-CCGG-3′) sites.