A cellular transcriptional coactivator that was originally identified by its requirement for the stable assembly IMMEDIATE-EARLY PROTEINS of the HERPES SIMPLEX VIRUS. It is a nuclear protein that is a transcriptional coactivator for a number of transcription factors including VP16 PROTEIN; GA-BINDING PROTEIN; EARLY GROWTH RESPONSE PROTEIN 2; and E2F4 TRANSCRIPTION FACTOR. It also interacts with and stabilizes HERPES SIMPLEX VIRUS PROTEIN VMW65 and helps regulate GENETIC TRANSCRIPTION of IMMEDIATE-EARLY GENES in HERPES SIMPLEX VIRUS.
