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. Author manuscript; available in PMC: 2008 Jan 22.
Published in final edited form as: Cell. 1983 May;33(1):261–272. doi: 10.1016/0092-8674(83)90355-0

Figure 4. Int Protection of the attP and attB Core Regions against Methylation by DMS.

Figure 4

The attP core region fragment from pMJB11 (containing only the core Int binding site, but no arm binding sites, see Experimental Procedures) was 5′-labeled in the lower strand (Bam site at +46) (A), or the upper strand (Hind III site at −70) (B), and methylated in the presence (+) or absence (−) of Int (see Experimental Procedures). An attB core region fragment from pMM291 (containing attB sequence from −17 to +21; Mizuuchi et al., 1981) was 5′-labeled in the lower strand (Hha site at 4257 in pBR322) (C), or the upper strand (Hga I site at 390 in pBR322) (D), and methylated in the presence (+) or absence (−) of Int. C+T chemical sequence markers were prepared by procedures of Maxam and Gilbert (1980). Samples were electrophoresed in 10% acrylamide–8 M urea gels (see Ross et al., 1979, 1982). Positions protected by Int against methylation (*). Smaller (*) indicates slight degree of protection. Positions of enhanced methylation in the presence of Int (→). The outermost affected positions in each site are numbered; see Figure 5 for identification of other protected positions.