GTF2H5
General transcription factor IIH subunit 5 is a protein that in humans is encoded by the "GTF2H5" gene. Function. The "GTF2H5(TTDA)" gene encodes a small (71 amino acid) protein that stabilizes the multi-subunit transcription repair factor IIH(TFIIH). TFIIH plays a key role in a major DNA repair process, nucleotide excision repair (NER), by opening the DNA double helix after the initial recognition of damage in one strand. This step is followed by excision of the damaged region to generate a single-strand gap, and then repair synthesis, using the undamaged strand as template, to accurately fill in the  gap. Disruption of the "GTF2H5(TTDA)" gene in a knockout mouse-model completely inactivates NER. In humans, mutation in any one of four genes can give rise to the trichothiodystrophy phenotype. These genes are "TTDN1", "XPB", "XPD" and "GTF2H5(TTDA)". Interactions. GTF2H5 has been shown to interact with GTF2H2 and XPB.