Histone H5 messenger RNA is polyadenylated.

In most known systems, histone mRNA lacks the poly(A) sequence at the 3' end of the molecule typical of most mRNAs. Furthermore, the synthesis of histones, unlike that of most proteins, is tightly coupled to DNA synthesis. Nevertheless, histone synthesis occurs in amphibian oocytes in the absence of DNA synthesis. Moreover, it has recently been found that in amphibian oocytes most of the histone mRNA is polyadenylated, and the polyadenylate is probably removed during maturation of the oocyte. Histone H5, an H1-like tissue-specific histone occurring only in nucleated erythrocytes, is also atypical in that it is synthesised in the absence of DNA synthesis during maturation of the red blood cells. We report here that H5 mRNA is polyadenylated.