Rous sarcoma virus genome is terminally redundant: the 5' sequence.

Abstract
When Rous sarcoma virus RNA is transcribed into DNA by the reverse transcriptase [EC 2.7.7.7], a tRNA primer is elongated into DNA. The primer is near the 5'' end of the virus genome; the 1st major DNA made is a run-off product extending 101 bases from the primer to the 5'' end of the template. This DNA molecule was studied to determine the sequence of the first 101 bases at the 5'' end of the Rous sarcoma virus genome (Prague strain, subgroup C). Twenty-one bases at the extreme 5'' end are also at the 3'' end of the virus genome; thus this virus is terminally redundant. The existence of this sequence repetition immediately suggests mechanisms by which the growing DNA copy can jump from the 5'' end to a 3'' end of the template and become circular. The sequence displays a possible ribosome binding site and enough secondary structure to permit a possible 5''-5'' linkage of viral RNA molecules.