Figure 2.

GCM specifically binds to an octamer sequence. (A) The GCM consensus-binding sequence. Forty-eight of the clones selected from a pool of random oligonucleotides on the basis of affinity to N243 were sequenced and aligned. Percentage values are the frequency of each base at each position. The most frequently present bases are highlighted and the derived consensus sequence is shown below. (B) Competition assays. Assays were performed using a 200-bp labeled DNA fragment B (see Fig. 3A) with protein N243 in lanes 2–10, and MBP-lacZα in lane 1 as a control. Unlabeled competitors were added to the reaction mixture in equal concentration to the labeled probe or in 10-, 100-, or 1000-fold molar excess. Absence of the competitor is indicated by minus signs. Addition of competitor a, which contains the consensus sequence, abolishes DNA-protein complex. Addition of competitor b, which lacks the consensus sequence, did not show competitive activity. Free probes (F) and DNA-protein complexes (B) are indicated.