Protein synthesis in tomato fruit locule tissue: The sites of synthesis and the pathway of carbon into protein.

The net increase in total protein during development of tomato fruit locule tissue has been further investigated with respect to the sites of protein synthesis within the cells. The results point to the plastids as being the major sites of protein synthesis. This is supported by radioisotope experiments in which labelled carbon from bicarbonate has been show to appear in protein at a higher rate than exogenously supplied amino acid. Isolated plastids incorporate carbon from bicarbonate, glucose and pyruvate into protein, and it is suggested that the pathway of carbon into protein involves photosynthetic pathways. The results are discussed with reference to possible differences between protein synthesis in plastids, and protein synthesis in the cytoplasm of plant cells.