The synthesis of proteins in the test-tube from purified mRNA molecules using cell extracts containing ribosomal sub-units, the necessary protein factors, tRNA molecules and aminoacyl tRNA synthetases, ATP, GTP, amino acids and an enzyme system for re-generating the nucleoside triphosphates. Prokaryotic translation systems are usually prepared from E. coli or the thermophilic bacterium, Bacillus stearothermophilus. Eukaryotic systems usually employ rabbit reticulocyte lysates or wheat germ.