2 MESSENGER-RNA SPECIES ENCODING THE DIFFERENTIATION-ASSOCIATED HISTONE H1(0) ARE PRODUCED BY ALTERNATIVE POLYADENYLATION IN MOUSE

Histone H1(0) is a differentiation-specific member of the histone H1 f amily. The accumulation of the protein is associated with the terminal stage of cell differentiation and is regulated at various levels. In mouse, the analysis of the: expression of the single copy gene encodin g H1(0) has shown that another H1(0)-related mRNA species (0.9 kb) is present in addition to the usual 2.1-kb mRNA. In this study, we have c loned and sequenced the smaller H1(0)-related mRNA. This mRNA seems to be produced by the use of an additional polyadenylation signal presen t in the 3' untranslated region (UTR) of the initial transcript. This smaller H1(0)-encoding mRNA is expressed only in mouse and is transfer red into polysomes as efficiently as the larger version upon the induc tion of cell differentiation. The use of the described polyadenylation site removes over 1 kb of the 3' UTR of H1(0) mRNA and seems to be in volved in the regulation of H1(0) mRNA stability.