Fig 1.

Proposed T box antitermination mechanism. The arrow indicates the transcription initiation site. The black rectangle represents the coding region of the regulated gene. Uncharged tRNA is postulated to interact with the nascent transcript at both the specifier sequence and the antiterminator bulge, stabilizing the antiterminator and preventing formation of the competing terminator. RNA polymerase (RNAP) then continues past the terminator region, and the full-length transcript is synthesized. “Factor?” indicates putative factor(s) that could modulate the leader RNA–tRNA interaction in vivo.