STRUCTURE, ASSEMBLY AND TARGETING OF WHEAT STORAGE PROTEINS

The functional properties of wheat flour in various food systems (most notably for breadmaking) are determined largely by the structures and interactions of the prolamin storage proteins, termed gliadins and gl utenins. It is therefore important to understand the structures of the individual proteins, their pathways and mechanisms of synthesis and d eposition, and their interactions with other flour components (for exa mple, starch and lipids) in order to manipulate the quality of wheat f or food and other uses, Me are using a range of biophysical and bioche mical approaches to determine the structures of individual proteins, u sing fractions purified from flour or expressed in heterologous system s. We are also isolating cDNAs for proteins involved in protein foldin g and assembly in the endoplasmic reticulum (protein disulphide isomer ase, BiP and peptidyl-proly cis-trans isomerase) and studying their in teractions with gluten proteins synthesised in E. coli. This work is c omplemented by immunocytochemical studies of gluten protein deposition in the leaves and seeds of transgenic tobacco plants, using wild-type proteins and mutants in which specific transit-targeting sequences ha ve been added or deleted. Taken together these results are giving a de tailed picture of the structure, synthesis, assembly and deposition of wheat gluten proteins.