THE GT-RICH SEQUENCE IN THE U5 REGION OF ROUS-SARCOMA VIRUS LONG TERMINAL REPEAT IS REQUIRED FOR TRANSCRIPTION TERMINATION AND 3'-PROCESSING

The sequences in the LTR of Rous sarcoma virus that are required for t ranscription termination and polyadenylation have been determined. A v ector containing LTR-neo-LTR has been constructed and deletions in the U5 region of the downstream LTR have been made. The DNAs from wild-ty pe and deletion mutant recombinant plasmids were introduced into QT6 c ells and G418-resistant transformants were selected. Those transforman ts with neo sequences in the arrangement, LTR-neo-LTR, were analyzed f or transcription termination and polyadenylation by Northern blot anal ysis and by S1 protection experiments. The results indicate that the p olyadenylation signal, AATAAA, located in the U3 region alone, is not sufficient for 3' end processing and that the sequence between +20 and +44 in the U5 region is absolutely required for transcription termina tion or endonudeolytic cleavage and polyadenylation.