FIG. 1.

Schematic representation of expression plasmids and analysis of HIV-1 Gag expression. (A) All expression plasmids contain part of the 5′ untranslated region of HIV-1 as well as the gag and PR coding regions. RNA elements derived from HIV-1 (RRE; pK-R-gpII) or from the IAP MIA14 (pK-M-gpII) were inserted 3′ of the coding region and are depicted as shaded (RRE) or solid (MIA14) boxes. At the top, the relative positions of the gag-PR region and of the RRE, as well as the coding exons for Rev, are highlighted in the HIV-1 genome. At the bottom, the relative position of the murine element is highlighted in the IAP genome. (B) Immunoblot analysis of transfected HeLa cells using antiserum against HIV-1 CA. Cells were transfected with plasmid pK-R-gpII (in the absence or presence of Rev [lanes 1 and 2]) or pK-gpII-M (containing the IAPE in sense or antisense [as.] orientation [lanes 3 and 4]). The cell lysates were normalized for transfection efficiency. The Gag polyprotein (Pr55) and CA are marked on the right; molecular mass standards (in kilodaltons) are given on the left. The additional proteins migrating between Pr55 and CA correspond to the Gag intermediate cleavage products MA-CA-NC and MA-CA.