FIG 7.

Model of the CITFA2-LC8 interaction and function for BES promoter transcription. Formation of a CITFA2-LC8 heterotetramer is a prerequisite for its assembly into the CITFA complex. While a stable partial CITFA complex is formed without CITFA2-LC8, only a fully assembled CITFA complex that includes CITFA2 and LC8 is able to bind promoter DNA. The BES promoter, with its two sequence blocks essential for CITFA binding (yellow), is shown here along with the TIS. Please note that, for ease of visualization and understanding, LC8's site of interaction with CITFA2 was not shown at its dimer interface, where it actually occurs. Promoter-bound CITFA is able, either directly or indirectly, to recruit RNA Pol I and enable transcription initiation.