Fig. 1.

Initial transcription and separation of nascent- versus released-transcripts. Denaturing electrophoresis of 5′-ApC dinucleotide radiolabeled RNAs generated from in vitro transcription reactions with archaeal components permits identification of specific transcripts (identified with solid arrows on the left). Two misincorporation products are visible in reaction #3 (identified with dashed arrows on the right). Reactions were separated into pellet (P) and supernatant (S) fractions to identify transcripts associated with the transcription apparatus (pellet fraction) from those transcripts released to solution (supernatant fraction). +116 nt transcripts represent run-off products. Radiolabeled ssDNA 10-bp markers (far left lane) serve as approximate size standards. Reactions resolved in lanes 1–3 each contain 5′-³²P-ApC and were supplemented with 200 μM: (1) ATP, GTP, CTP, and UTP; (2) only ATP, GTP, and UTP; (3) only GTP