Transcription Factor II H (TFIIH)
• One of several general transcription factors that make up the RNA polymerase II preinitiation complex.
• Consists of ten subunits, 7 of which (XPD, XPB, p62, p52, p44, p34 and TTDA) form the core complex.
• ERCC2/XPD and ERCC3/XPB, have helicase and ATPase activities and help create the transcription bubble.
• The cyclin activating kinase-subcomplex (CDK7, MAT1, and cyclin H) are needed to phosphorylate the CTD of RNA Pol II and is linked to the core via the XPD protein