Diagram of the stabilization assay. In vitro-assembled HIV-1 CA-NC
complexes, shown here as tubular structures, are formed by monomeric recombinant
HIV-1 CA-NC fusion proteins under highly ionic conditions and recapitulate the
surface of the HIV-1 core. When HIV-1 CA-NC complexes are incubated in
destabilization buffer, they disassemble spontaneously. Disassembled capsids are
layered on top of a 70 % sucrose cushion; however, the disassembled capsid does
not cross the cushion after spinning at 100,000 × g for
1 h. In contrast, incubation of HIV-1 CA-NC in stabilization buffer preserves
the assembled structures, which pellet when layered onto a 70 % sucrose cushion
with spinning at 100,000 × g for 1 h. Input, a fraction
of the sample layered onto the sucrose cushion before the centrifugation step.
Pellet, a fraction of the capsid pelleted after the sample has been centrifuged
at 100,000 × g for 1 h. Input and pellet samples were
analyzed by Western blotting using anti-p24 antibodies.