Fuente: WIPO "tomato" The present invention relates generally to the use of a set of engineered polypeptides in defined oligomeric states that may be used to generate calibration curves. Further, the invention also relates to the polypeptides, nucleic acid molecules that encode said polypeptides for expression in plants, plant cells, or plant seeds, and methods of their use in determining the oligomerisation state of proteins of interest in plants.