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. 1999 Sep 28;96(20):11134–11139. doi: 10.1073/pnas.96.20.11134

Figure 1.

Figure 1

ATM binds to DNA. (A) HeLa nuclear extract (ON) was bound to either streptavidin iron oxide beads (−DNA) or streptavidin iron oxide beads bearing a 50-mer ds DNA oligonucleotide (+DNA). After extensive washing, ATM was eluted in 500 mM KCl. Eluted proteins were subjected to 7% SDS/PAGE and ATM visualized by Western blotting using ATM.B antiserum. Equivalent fractions were probed for Sp1 and RNA polymerase II (Pol II). (B) ATM binding to DNA oligonucleotides depends on length. ATM-enriched extract (ON) was bound to streptavidin iron oxide beads attached to dsDNA of various sizes (15, 25, or 50 bp). After extensive washing, ATM was eluted sequentially with 100, 250, and 500 mM KCl. Eluates were analyzed as in A. (C) ATM is competed effectively by an excess of ssDNA and supercoiled DNA but not by poly-C or poly-CG. Washing, elution, and ATM detection was as above.