MAJOR LATE ADENOVIRUS TYPE-2 TRANSCRIPTION UNIT - TERMINATION IS DOWNSTREAM FROM THE LAST POLY(A) SITE

Late in adenovirus type-2 (Ad-2) infection of [human cervical carcinoma] HeLa cells the majority of viral RNA synthesis occurs from a transcription unit that extends between 16 and 100% on the physical map of the Ad-2 genome. Poly(A) is added to RNA at 5 distinct sites within the transcription unit. As many as 13 different mRNA can be processed from the primary RNA transcripts of this region of the genome. Examination of nuclear RNA in several different types of experiments (RNA fingerprint studies and hybridization of pulse-labeled nascent RNA and labeled nuclear RNA synthesized after UV irradiation to an ordered set of restriction endonuclease-generated DNA fragments) indicates that the mRNA 3'' terminus most distance from the promoter does not correspond to the RNA polymerse termination site for the transcription unit. Transcription continues .apprx. 2500-3000 residues beyond the 3'' terminus of the most promoter distal mRNA (localized between coordinates .**GRAPHIC**. and .**GRAPHIC**. and into the region .**GRAPHIC**. on the Ad-2 physical map. The occurrence of RNA termination sites distal to the poly(A) site is discussed as a general feature of transcriptional unit design in animal cells.