TFIIA is a component of the transcription machinery of RNA polymerase II and implicated in the regulation of basal transcription. Interacts with TBP (the TATA-binding protein). TFIIA is a heterodimer composed of the large TOA1 and a small TOA2 subunits. Interacts with KAP122. Imported to nucleus via interaction with KAP122. Belongs to the TFIIA subunit 1 family.