Ej. Platt et Ok. Haffar, CHARACTERIZATION OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 PR55(GAG) MEMBRANE ASSOCIATION IN A CELL-FREE SYSTEM - REQUIREMENT FOR A C-TERMINALDOMAIN, Proceedings of the National Academy of Sciences of the United Statesof America, 91(10), 1994, pp. 4594-4598
Association of the human immunodeficiency virus type 1 (HIV-1) gag pol
yprotein precursor with cellular membranes is necessary for assembly o
f virions. We used in vitro synthesized HIV-1 gag to study its associa
tion with isolated cellular membranes. Rabbit reticulocyte lysates pro
grammed with HIV-1 gag mRNA incorporated [S-35]methionine and [H-3]myr
istate into two predominant species of 55 kDa and 40 kDa. Radioimmunop
recipitation with HIV-1-specific antibodies suggested that the 55-kDa
protein represented the polyprotein precursor (Pr55(gag)), while the 4
0-kDa protein was a mixture of N- or C-terminal truncations of the gag
precursor. The Pr55(gag) protein bound to cellular membranes, while t
he 40-kDa mixed protein species did not. Membrane binding studies with
C terminus-truncated and point mutants revealed that the seven-amino
acid sequence located between the two Cys-His arrays in the nucleocaps
id region was necessary for stable association to occur. Therefore, we
propose that signals in addition to myristate are required for the me
mbrane association of HIV-1 gag proteins and that these signals includ
e a domain in the nucleocapsid protein.