Frequent occurrence of short complementary sequences in nucleic acids.

The hypothesis, that nucleic acids which code specifically interacting receptor and ligand proteins contain complementary sequences was tested. Human insulin mRNA (HSINSU) contained 16 sequences which were 23.8 +/- 1.4 nucleotides long and were complementary to the insulin receptor mRNA (HSIRPR, 74.8 +/- 1.9% complementary matches, p less than 0.001 compared to randomly occurring matches). However, when examining 10 different nucleic acids (coding proteins not interacting with the insulin receptor), 81 additional sequences were found which were also complementary to HSIRPR. Although the finding of short complementary sequences was statistically highly significant, we concluded that this is not specific for nucleic acids coding specifically interacting proteins.