Component of RNA polymerase I core factor complex that acts as a GTF2B/TFIIB-like factor and plays a key role in multiple steps during transcription initiation such as pre-initiation complex (PIC) assembly and postpolymerase recruitment events in polymerase I (Pol I) transcription. Binds rDNA promoters and plays a role in Pol I recruitment (By similarity). Required for the development of the one-cell zygote and endosperm in embryos (PubMed:15634699). Required for micropylar pollen tube guidance, but has no effect on ovule development and gametophytic cell fate specification (PubMed:18055609). May regulate the transcription of secreted cysteine-rich peptide (CRP) genes in the embryo sac (PubMed:26462908). Interacts with TFIIF (PubMed:18055609, PubMed:26462908). Interacts with MEE14/CBP1, TBP1 and NRPB1 (via CTD) (PubMed:26462908). Expressed at high levels in seedlings, inflorescences and young siliques and at lower levels in roots. Not detected in leaves and stems. Detected in root tips and shoot apical meristems, in anthers, primarily in microspores with weaker expression in mature pollen grains and in the central cell of the mature female gametophyte. Not expressed in synergids, egg cells, antipodal cells, endosperm cells and fertilized egg cells. Expression in central cell of the mature female gametophyte is pollination independent. Although it shares weak sequence similarity with GTF2B/TFIIB, displays a similar subdomain organization as GTF2B/TFIIB, with a N-terminal zinc finger, a connecting region (composed of B-reader and B-linker regions), followed by 2 cyclin folds. Disrupted function of the female gametophyte. Defective in micropylar pollen tube guidance leading to zygotic lethality. Expression of MEE12 in the central cell alone is sufficient to restore the normal pollen tube guidance phenotype. Belongs to the RRN7/TAF1B family.