Abstract
The integrated DNA copies (proviruses) of RNA tumour virus genomes are flanked by long terminal repeat (LTR) sequences, which are generated by the duplication of segments present at both ends of the viral RNA1. LTRs vary in length from 330 (ref. 2) to 1,328 (this paper) base pairs (bp). The primary viral transcript starts in the left LTR (L-LTR) and terminates in the right LTR (R-LTR)3. We have now sequenced both LTRs from an inherited (endogenous) mouse mammary tumour virus (MMTV) of the GR strain. This provirus, which is one of five present in the haploid genome of GR mice4, does not produce virus5 and is not identical with the exogenous MMTV of GR mice6. The provirus (GR40) could nevertheless be transcribed and its transcription hormonally regulated after cloning and transfection into mouse L cells7. The LTRs are identical and exhibit the following features: a terminal inverted 6-bp repeat, a Goldberg–Hogness (TATAAA) sequence, sequences which have been implicated in polyadenylation and the termination of transcription, and an open reading frame. The open reading frame of the R-LTR starts at the env/LTR junction and encodes a 36,700-molecular weight (Mr) protein. The open reading frame of the L-LTR extends into the adjacent mouse sequence. A host sequence of 6 bp at the site of integration into the mouse chromosome is directly repeated.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
