FIG. 4.

SUMO-1 is incorporated into HIV-1 virions. Virions produced by 293T cells cotransfected with pNL4-3 or pNL4-3K27R and a HASUMO-1 expression plasmid were purified through a 25% sucrose cushion. After subtilisin digestion, virions were analyzed by Western blotting using the indicated antibodies. To measure viral genomic RNA incorporation, virions were normalized by exogenous RT assay, loaded onto a nylon membrane, and probed with a ³²P-end-labeled DNA oligonucleotide specific for HIV-1 genomic RNA.