Similar linear arrangement of putative domain structures of THOV GP and AcMNPV GP64 compared to domain structures of VSV G and HSV-1 gB. Amino acids are numbered beginning after the putative signal sequences in VSV G, but at the beginning of the signal sequence of HSV-1 gB. Arrows indicate G and gB truncations of the forms used for crystallography. Solid lines represent cysteine bonding in VSV G and HSV-1 gB. Black boxes represent hydrophobic regions, with violet representing the transmembrane anchor (TM) . Dashed lines represent potential cysteine bonding in THOV GP and AcMNPV GP64. Panel A: class III penetrene domain nomenclature and coloring as in Fig. 1. Panel B: domain nomenclature and color coding schemes used previously for VSV G  and for HSV-1 gB . Hatched boxes in VSV G represent "hinge" aa not assigned to domains.