TFIIA is a component of the transcription machinery of RNA polymerase II and plays an important role in transcriptional activation. TFIIA in a complex with TBP mediates transcriptional activity. TFIIA is a heterodimer of the large unprocessed subunit 1 and a small subunit gamma. It was originally believed to be a heterotrimer of an alpha, a beta and a gamma subunit. Belongs to the TFIIA subunit 2 family.