Plays an essential role in egress of virus particles from the nucleus, cytoplasmic envelopment and virus-induced cell fusion. Forms a functional protein complex with gK and this interaction is absolutely essential for their coordinate intracellular transport, gK glycosylation, expression on host cell surface, and function. Together, they modulate gB-mediated virus-induced cell fusion and virion egress and therefore actively participate in these processes. Interacts with gK (via N-terminus); this interaction plays a role in the coordinate transport of UL20 and gK to the trans-Golgi network (TGN), and is required for their cell surface expression. Interacts with gB. During virion morphogenesis, this protein probably accumulates in the trans-Golgi where secondary envelopment occurs. It is probably transported with gK to the cell surface from where it is endocytosed and directed to the trans-Golgi network (TGN). Belongs to the alphaherpesvirinae UL20 family.