A consensus repeat sequence from the human insulin gene linked polymorphic region adopts multiple quadriplex DNA structures in vitro.

A hypervariable region consisting of repeats of a 14 base pair (bp) consensus sequence ACAGGGGT(G/C)(T/C)GGGG is located 363 bp upstream of the human insulin gene. Different repeat numbers of this oligonucleotide give rise to a polymorphism, and so this region is commonly known as the insulin gene linked polymorphic region (ILPR). Here we present evidence, based on the mobility in non-denaturing polyacrylamide gels of two dissimilarly sized oligonucleotides containing the ILPR consensus sequence, that this sequence can adopt a number of quadriplex DNA structures in vitro.