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. 2001 Aug 28;98(19):10875–10879. doi: 10.1073/pnas.191224698

Figure 2.

Figure 2

Nuclease and salt resistance of particles assembled in vitro and of authentic, immature particles. Particles assembled in buffer B (A), buffer B plus 5% rabbit reticulocyte lysate (B), or buffer B plus 2 μM IP5 (C), were treated with RNase A (lanes 2) or NaCl (lanes 3). Gag proteins in particles pelleted after treatment were examined by SDS/PAGE and Coomassie blue staining. We estimate that >90% of the Gag protein was solubilized in A (lanes 2 and 3), whereas >90% remained pelletable in B and C (lanes 2 and 3). (D) Immature MoMuLV and HIV-1 virions produced in mammalian cells were analyzed separately (lanes 1 and 2, respectively) or were mixed together (lanes 3–9) and treated with RNase A (lanes 6 and 7) or NaCl (lanes 8 and 9). They were also digested with HIV-1 PR to confirm that the lipid envelope was removed by the detergent (lane 3), or sedimented without RNase or NaCl treatment to confirm that the particles are stable in buffer B (lanes 4 and 5). Gag proteins in the samples in D were detected by immunoblotting with antibodies against the CA proteins of both HIV-1 and MoMuLV. We estimate that >90% of the HIV-1 Gag protein was still pelletable after NaCl or RNase treatment. P, pellet; S, supernatant.