AbstractSimple repetitive DNA sequences have been regarded as mere “junk” present in all eukaryotic genomes. In fact, mixed simple repeat (gt)n(ga)msequences are present in major histocompatibility complexMHC‐DRBgenes for long evolutionary times, including such distant animals as artiodactyla and man. We describe herein an unsophisticated method which reveals that at least certain simple repetitive (gt)n(ga)msequences bind nuclear proteins and show characteristics of a specific DNA‐protein interactionviagel reta