Figure 1

Fusion proteins associating GFP with various protein transduction domains and either ubiquitin or SUMO-1. (a) Schematic representation of the different types of fusion proteins. Vectors were constructed to express GFP as a fusion with the FLAG epitope (F) and with a protein transduction domain (PTD) giving proteins FPG. For other constructs, ubiquitin (Ub) or SUMO-1 (SUMO) was inserted between the PTD and the GFP fragments, so as to allow delivery of GFP, through cleavage after the diglycine motif (GG) present within both ubiquitin and SUMO-1. (b) Different oligonucleotides were designed and annealed, so as to generate 9 different possible PTDs. These sequences were inserted after those coding for the FLAG epitope. These PTDs corresponded to the basic domain of the HIV-1 Tat protein (PTD1), to an Ala-rich derivative (PTD2), to poly-arginine motifs (PTD5, PTD7, PTD8) and to a polylysine motif (PTD9). PTD3, 4 and 6 were derived from the alpha-helical domain present within ubiquitin.