Restriction landmark genomic scanning (RLGS) is a method for visualizing restriction landmarks, employing direct labeling of restriction sites of genomic DNA and high-resolution two-dimensional electrophoresis. We determined the conditions for both the first and second dimensions of RLGS that define all of the restriction fragments which carry the NotI landmark. Using this system, we determined the number of cleavable NotI sites of genomic DNA from the mouse kidney (C57BL/6) and from the human placenta. The mouse and human genomes were cleaved at 2,380 +/- 80 sites (4,760 +/- 160 spots) and 3,240 +/- 110 sites (6,480 +/- 220 spots), respectively with NotI.