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. 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, and in glioblastoma cells by interacting with host EPHA2. The gH-gL-UL128-UL130-UL131A pentamer is essential for viral entry in epithelial, endothelial and myeloid cells via interaction with host NRP2 