[mRNA sequences complementary to the double-stranded regions of pre-mRNA. Hybridization experiments using RNA mercuriation and chromatography on sulfhydryl-Sepharose].

It was demonstrated that 4--6% of the sequences of mouse cell pure polysomal poly (A)mRNA are able to form stable duplexes during hybridization with the excess of double-stranded structures of nuclear pre-mRNA (double-stranded RNA). Hybridization of mRNA with the excess of mercuriated double-stranded RNA and chromatography of the hybrids on sulfhydril-sepharose was investigated. It was found that only 7--11% of the molecules of polysomal poly(A)+mRNA are able to form thermostable hybrids with sequences of double-stranded RNA. It may be supposed that in the population of mRNA there are relatively few molecules (about 5%) which contain sequences originated from long hairpin structures of pre-mRNA. Moreover, probably, there is a number of mRNA molecules (about 5% of the mRNA population) which are complementary in the entire length to "non-hairpin" double-stranded regions of pre-mRNA.