HIV-1 antigen Nef, Green Fluorescent Protein (GFP), and the fusion protein GFP-Nef ("Green Fluorescent Nef") were synthesized in bacterial cell-free system with continuous supply of substrates and continuous removal of low-molecular-weight products through a dialysis membrane during incubation, the so-called continuous-exchange cell-free (CECF) system. The identity of synthesized proteins was confirmed by electrophoretic mobility, Western blotting, and GFP fluorescence. The system produced several nanomoles (hundreds of mug) of each protein per mi of the reaction mixture. Construction of GFP-fused proteins is considered as a general strategy for visualization and monitoring of cell-free production of the proteins that have no easily testable functions.