The Sudan ebola virus (SUDV) glycoprotein (GP) is an envelope glycoprotein that is present on the virion surface and is involved in receptor binding and mediating viral entry. It is composed of a trimer of heterodimers (GP1/GP2), where GP1 and GP2 remain covalently linked by a disulfide bond9, and the resulting GP1-GP2 pair trimerizes to form a ~450 kDa envelope spike on the viral surface. GP is synthesized as a single polypeptide of 676 amino acids in length that is post-translationally cleaved by furin to yield two subunits, GP1 and GP2. The GP1 subunit contains two heavily glycosylated domains, the glycan cap and the mucin-like domain (MLD). The glycan cap contains only N-linked glycans, whereas the MLD contains both N- and O-linked glycans. All 15 N-glycosylation sites of GP1 could be removed without compromising the expression of GP. In the endosome, a flexible loop containing GP1 residues 190 213 is cleaved by host cathepsins. This cleavage releases the glycan cap and mucin-like domains from GP1. The GP1 subunit is responsible for receptor binding and attachment to new host cells.