Envelope glycoprotein necessary for proper maturation of gM and modulation of its membrane fusion activity. Also plays a critical role in virion morphogenesis. Interacts (via N-terminus) with gM (via N-terminus). The gM-gN heterodimer forms the gCII complex. When coexpressed with gM, localizes in the host trans-Golgi network. O-glycosylated. Belongs to the herpesviridae glycoprotein N family.