Recruits TFIIH to the initiation complex and stimulates the RNA polymerase II C-terminal domain kinase and DNA-dependent ATPase activities of TFIIH. Both TFIIH and TFIIE are required for promoter clearance by RNA polymerase. Tetramer of two alpha and two beta chains (PubMed:1956398). Interacts with TAF6/TAFII80 (PubMed:7667268). Interacts with ATF7IP (PubMed:19106100). Interacts with SND1 (PubMed:7651391). (Microbial infection) Interacts with varicella-zoster virus IE63 protein. Belongs to the TFIIE alpha subunit family.