(A) Approximate location of gH functional domains are shown including the signal sequence (residues 1–17), DI (residues 18–65), DII (residues 66–344), DIII (residues 345–529), DIV (residues 530–679), transmembrane domain (residues 680–698) and the cytoplasmic tail (residues 699–706). (B) FLAG tagged mutants: sgH, DI-II-III, DI-II, DI are all c-terminally tagged with the FLAG epitope followed by a stop codon, as indicated. None of the mutants contain the transmembrane domain nor the cytoplasmic tail of gH. (C) Wild type gL includes the signal sequence (residues 1–23) followed by a single domain (residues 24–137).