Multifunctional regulator of the expression of viral genes that mediates nuclear export of viral intronless mRNAs. This immediate early (EI) protein promotes the nuclear export of viral intronless mRNAs by interacting with mRNAs and host NXF1/TAP (By similarity). Homodimer. Homodimerization is required for transactivation. Associates in a complex with RNA, and host export factors NXF1/TAP and ALYREF; these interactions allow nuclear export of viral transcripts. Interacts with three host shuttling SR proteins SRSF1, SRSF3 and SRSF7. Interacts with host SRPK1. Interacts with IE62; this interaction enhances IE62 transactivation (By similarity). Shuttles between the nucleus and the cytoplasm. Binds viral intronless RNAs and SR proteins through the Arg-rich region. Belongs to the HHV-1 ICP27 protein family.