The heterodimer glycoprotein H-glycoprotein L is required for the fusion of viral and plasma membranes leading to virus entry into the host cell. Following initial binding to host receptor, membrane fusion is mediated by the fusion machinery composed of gB and the heterodimer gH/gL. May also be involved in the fusion between the virion envelope and the outer nuclear membrane during virion morphogenesis (By similarity). In human cytomegalovirus, forms two distincts complexes to mediate viral entry, a trimer and a pentamer at the surface of the virion envelope. The gH-gL-gO trimer is required for infection in fibroblasts by interacting with host PDGFRA. The gH-gL-UL128-UL130-UL131A pentamer is essential for viral entry in epithelial, endothelial and myeloid cells via interaction with host NRP2 (By similarity). Interacts with glycoprotein L (gL); this interaction is necessary for the correct processing and cell surface expression of gH. The heterodimer gH/gL seems to interact with gB trimers during fusion (By similarity). Forms the envelope pentamer complex (PC) composed of gH, gL, UL128, UL130, and UL131A. The pentamer interacts with host NRP2. Forms the envelope trimer complex composed of gH, gL, and gO (PubMed:9733861). The trimer interacts with host PDGFRA (By similarity). Interacts with UL116 (By similarity). During virion morphogenesis, this protein probably accumulates in the endosomes and trans-Golgi where secondary envelopment occurs. It is probably transported to the cell surface from where it is endocytosed and directed to the trans-Golgi network (TGN). N-glycosylated, O-glycosylated, and sialylated. Belongs to the herpesviridae glycoprotein H family.