text: Typical stages in a tRNA (also termed class II) gene initiation:
  *TFIIIC (Transcription Factor for polymerase III C) binds to two intragenic (lying within the transcribed DNA sequence) control sequences, the A and B Blocks (also termed box A and box B).
  *TFIIIC acts as an assembly factor that positions TFIIIB to bind to DNA at a site centered approximately 26 base pairs upstream of the start site of transcription.
  *TFIIIB is the transcription factor that assembles Pol III at the start site of transcription. Once TFIIIB is bound to DNA, TFIIIC is no longer required. TFIIIB also plays an essential role in promoter opening.