Developing systems for the analysis of membrane proteins is fundamentally important for the identification of pharmaceutically active substances. This involves a particular focus on pharmacological characterization, the modification and functional examination of the cell-free production of membrane proteins. Ion channels, transport proteins and G protein-coupled receptors are a particular research focus. The introduction of fluorophores at specific positions allows multimeric membrane proteins to be used in analysis. The integration of modified, non-canonic amino acids during protein synthesis is carried out by using chemical or enzymatically pre-aminoacylated tRNAs. Defined protein conjugates with biotinylated or fluorescence labeled groups are produced both in prokaryotic and eukaryotic cell-free systems. Marking a specific location on the protein provides a non-invasive method for the functional analysis of the synthesized membrane protein. This involves an electrophysiological characterization of ligand-gated and voltage-gated ion channels, which are analyzed with regard to the identification of new pharmaceuticals.