Site on the RNA of an avian sarcoma virus at which primer is bound.

In vitro transcription of the avian tumor virus RNA by RNA-directed DNA polymerase is initiated on the unique cellular 4S RNA. Previous studies have shown that on the average there is one such RNA primer hydrogen bonded to each viral 35S RNA. The present study confirms that finding and demonstrates that, at least for the majority of 35S RNA molecules, the primer is bound at a site close to the 5'-terminus.