Abstract
The replication dependent histone transcripts terminate with a highly conserved stem-loop structure. This feature distinguishes them from most other eukaryotic mRNAs which end with a poly(A) tail. The 3' terminus of histone mRNA is a main determinant for rapid turnover of these transcripts. In this study, we report the identification of two cytoplasmic protein complexes that interact in a sequence specific fashion with 3' terminal sequences of a mouse histone H4 and a human histone H2A mRNA. The binding activities are conserved from frog to man. At least a fraction of one of the protein complexes appears to be specifically associated with polysomes. The evidence for an involvement of the observed protein complexes in turnover of histone transcripts is discussed.