A mouse histone H4 gene carried by an SV40 vector is accurately expressed in infected monkey cells

We present evidence that a cloned mouse histone H4 gene contains all the information required for the generation of functional H4 mRNA. The cloned mouse gene, flanked by spacer sequences extending 228 bp at the 5' end and 1100 bp at the 3' end, was introduced into the late region of the SV40 genome and the recombinant virus was used to infect cultured monkey kidney cells. RNA mapping studies demonstrated that the H4 transcripts from the infected cells could be initiated at either the mouse or viral promoter and that the majority of the RNA had the same 3' end as authentic mouse H4 RNA. The mouse RNA was incorporated into polysomes and there was a specific increase in H4 protein synthesis in cells infected with the recombinant virus. The distribution of the H4 transcripts between the polysomal and postpolysomal fractions suggests that RNA initiated at the mouse promoter is more efficiently bound to polysomes than is the hybrid RNA initiated at the SV40 promoter.