Nucleoside 5'-[gamma-S]triphosphates will initiate transcription in isolated yeast nuclei.

Transcription was carried out in isolated nuclei by endogenous ribonucleic acid (RNA) polymerase in the presence of nucleoside 5'-[gamma-S]triphosphates. The resulting 5'-gamma-thiophosphate on the synthesized RNA allows separation of in vitro initiated RNA from bulk RNA. Analysis of this in vitro initiated RNA shows that 5S RNA and pre-tRNA are initiated in vitro by RNA polymerase III. Yeast RNA polymerase III also reinitiates discrete distribution of RNA species as large as 28 S. The RNA populations initiated with adenosine 5'-[gamma-S]triphosphate and guanosine 5'-[gamma-S]triphosphate are different.