In addition to eleven glycoproteins, the herpes simplex virus type 2 (
HSV-2) genome encodes several proteins with potential membrane spannin
g segments but no asparagine-linked carbohydrates, One of these is UL4
5. Fractionation of infected cells showed that HSV-2 UL45 is an integr
al membrane protein, and analysis of UL45 mutants with potential glyco
sylation sites showed that it has a type II membrane orientation, the
first HSV protein known to have this orientation. Furthermore, it is d
etectable in infected cells at a time similar to that when glycoprotei
ns gB and gD are detected, consistent with a role in cell-cell fusion,
which has previously been found for HSV-1 UL45.