Transcription of 5S RNA genes containing insertion mutation and the assembly of preinitiation complexes

The transcription of Xenopus 5S RNA genes containing insertions in and around the intragenic control region has been analyzed in a HeLa cell-free system. A 15 bp insertion within the intragenic region greatly diminished binding of TFIIIA and concomitantly reduced binding of TFIIIB and transcription in vitro. This study helps to define more precisely the promoter organization of Xenopus 5S RNA genes for the efficient interactions with transcription factors.