Role for the amino-terminal region of human TBP in U6 snRNA transcription

Basal transcription from the human RNA polymerase III U6 promoter depends on a TATA box that recruits the TATA box-binding protein (TBP) and a proximal sequence element that recruits the small nuclear RNA (snRNA)-activating protein complex (SNAP(c)). TBP consists of a conserved carboxyl-terminal domain that performs all known functions of the protein and a nonconserved amino-terminal region of unknown function. Here, the aminoterminal region is shown to down-regulate binding oi TBP to the U6 TATA box, mediate cooperative binding with SNAP(c) to the U6 promoter, and enhance U6 transcription.