FIG. 4.

Role of flanking regions on HIV PR and B3 proteolytic activity in E. coli. The AC molecules and HIV (or B3) PRs are schematized as in Fig. 1. The phenotype of DHT1 cells expressing the indicated proteins was scored on MacConkey-maltose plates plus kanamycin and ampicillin (lanes 1 to 6) or plus kanamycin (lanes 7 to 12). β-Galactosidase activities and cAMP levels were measured on liquid cultures grown overnight at 30°C in LB supplemented with appropriate antibiotics, as described in Materials and Methods. The plasmids expressing the indicated hybrid proteins were as follows: lane 1, pKACp5 + pUCB3-S; lane 2, pKACp5 + pUCB3-L/S; lane 3, pKACp5 + pUCB3-S/L; lane 4, pKACp5 + pUCB3-L; lane 5, pKACp5 + pUCHIV-L/S; lane 6, pKACp5 + pUCHIV-S/L; lane 7, pKACB3-S; lane 8, pKACB3-L/S; lane 9, pKACB3-S/L; lane 10, pKACB3-L; lane 11, pKACPR-L/S; 12, pKACPR-S/L.