Butyrate induced accumulation of a 2.3 kb polyadenylated H1° histone mRNA in HeLa cells

Sodium butyrate was used to induce the accumulation of human H1° mRNA in HeLa cells. The length of this mRNA (2,300 nucleotides) was determined by Northern blot hybridization and S1 nuclease analysis using a human H1° gene probe. The mRNA shows long 5′ and 3′ non coding segments and it is polyadenylated. The signal for this step of mRNA maturation (cleavage and polyadenylation) appears to be the hexanucleotide AAUAAA in analogy to most (other than histone) mRNA species. Thus, the mode of maturation of H1° mRNA differs, on one hand, from that of the cell cycle dependent mRNA species, where it is based on a specific stem-and-loop structure. On the other hand, the 3′ end of H1° mRNA varies from H5 mRNA, which is characterized by two unique dyad symmetry structures at its 3′ end.