Archaeal Spt4/5 stimulates transcription elongation. Transcription assay using a synthetic elongation scaffold and recombinant 10-subunit M. jannaschii RNAP (200 nM). Transcript synthesis was monitored over a time course of 2, 5, 10 and 20 min in the absence of NTS (A), and 20, 40, 90 and 300 s in the presence of NTS (B). Recombinant Spt4/5 (10 µM) was added to the reaction in conjunction with RNAP. The full length ‘run off' transcript was quantitated in the absence (C) and presence of the NTS, and normalized to the reaction end point in the absence of Spt4/5 (20 min and 300 s w/o NTS, C, and plus NTS, D, respectively). The gels (A and B) are representative and all quantitations are based on at least three independent experiments (arbitrary units, AU).