General Transcription Factor IIIA (GTF3A)

General Transcription Factor IIIA is a zinc finger protein with nine Cis-His zinc finger domains. It functions as an RNA polymerase III transcription factor to induce transcription of the 5S rRNA genes.

The protein binds to a 50 bp internal promoter in the 5S genes called the internal control region (ICR), and nucleates formation of a stable preinitiation complex. This complex recruits the TFIIIC and TFIIIB transcription factors and RNA polymerase III to form the complete transcription complex.The protein is thought to be translated using a non-AUG translation initiation site in mammals based on sequence analysis, protein homology, and the size of the purified protein.