The processing properties of wheat flour are largely determined by the structures and interactions of the grain storage protein, the so called “gluten proteins”. The synthesis, folding and deposition of the gluten proteins take place within the endomembrane system of the plant cell. Several studies have suggested that two trafficking pathways occur in wheat, with the proteins either being transported via the Golgi apparatus into the vacuole or assembling within the ER to form protein bodies that are subsequently internalized into vacuoles by a process analogous to autophagy. The precise routes of trafficking and deposition of individual gluten proteins remain unclear and so are the molecular and cellular mechanisms regulating their sorting in the two pathways.