Figure 4.

Glucose-induced protein-DNA binding activity is specific to GluRE DNA. To determine the binding specificity of glucose induced nuclear factor(s) to GluRE DNA, competition experiments were performed using ³²P-labeled GluRE DNA in the presence of unlabeled GluRE DNA or unlabeled GAGA DNA (previously shown as a growth response enhancer element; Wyse et al., 2000). Lane 1, labeled probe in the absence of nuclear extract; lane 2, in the presence of high glucose (25 mM) exposed nuclear extract; lane 3, nuclear extract incubated with labeled probe to which 50-fold excess of unlabeled GluRE was added as a competitor; and lane 4, nuclear extract with labeled probe to which 50-fold excess of unlabeled GAGA was added as a competitor. The arrow indicates the position of the protein–DNA complex.