A transcription factor TFIIIB-beta complex that contains the TATA-binding protein (TBP), B'' and a specialized homolog of the conserved subunit BRF referred to as BRFU or TFIIIB50, which found in human but not conserved in yeast; the complex is involved in the regulation of transcription from type 3 (upstream) RNA polymerase III promoters.
transcription factor TFIIIB-alpha complex