Figure 2.

Examples of successful application of the heterologous fusion-protein approach. The structures are not shown on the same scale. (a) Cartoon diagram of the structure of HTLV-1 gp21 (subunits are shown in different colours) fused at the N-terminus to MBP (in different shades of grey) with a three-Ala linker (red; PDB entry 1mg1; Kobe et al., 1999 ▸). (b) Cartoon diagram of the structure of β₂-adrenergic receptor (β₂AR; blue) with T4 lysozyme (T4L; grey) inserted into a loop in β₂AR (Rosenbaum et al., 2007 ▸; PDB entry 2rh1). (c) A view of crystal-packing interactions for the β₂AR-T4L fusion protein [shown and coloured as in (b)]. Note the crystal contacts between the fusion partner T4L and the soluble portion of β₂AR. (d) Cartoon diagram of the structure of the complex of the extracellular domains of TLR1 (green) and TLR2 (blue) (Jin et al., 2007 ▸; PDB entry 2z7x). Both proteins are fused at the C-terminus to VLR as the fusion partner (grey). All structure figures were produced with PyMOL (Schrödinger).