Figure 1.

Methylated DNA affinity precipitation. (A) A methylated, concatamerized oligo is incubated with oocyte extract to probe for proteins with methyl-CpG binding activity. After performing the necessary washing steps, the eluate contains proteins specifically binding methylated DNA. (B) The concatamerization of the oligo is monitored by agarose gel electrophoresis. The majority of concatamerized DNA consists of fragments ranging in size from 100 - 300 bp. (C) The extent of oligo methylation is measured by restriction digestion. MspI enzyme cuts both methylated and unmethylated DNA whereas its isoschizomer HpaII cuts only unmethylated DNA. (D) The binding of the biotinylated oligo to streptavidin beads is measured by agarose electrophoresis. An aliquot of the probe before incubation with streptavidin beads (before - B) is compared to a probe aliquot after 30 minutes of incubation time (after - A).