Required for efficient transcription initiation by RNA polymerase I. Required for the formation of the competent preinitiation complex (PIC). Dissociates from pol I as a consequence of transcription. In vitro, cannot activate transcription in a subsequent transcription reaction. Interacts with TAF1B. Interacts with POLR1F, EIF3L and TAF1C (By similarity). Phosphorylated at Thr-198 by MAPK9/JNK2, which abrogates initiation complex formation. Belongs to the RRN3 family.