Protein Folding in the Plant Cell

Whole-genome sequencing projects have drastically changed the landscape of biological research. The lexicon of contemporary biology contains a plethora of new terms, including: genomics, research pertaining to the genome; proteomics, description of the protein complement of an organism; and bioinformatics, the collection and interpre- tation of biological information (primarily nucleic acid and amino acid sequence data) (Bouchez and Hofte, 1998). However, obtaining sequence information is not an end unto itself. It is essential that the products of these genes be identified and their function and physiological significance discovered (Bork et al., 1998; Saier, 1998). In complex eu- karyotes such as flowering plants, as many as 5 3 104 genes can be selectively expressed in individual cells. It is the products of these genes, the proteins, that determine the fate and function of the cells. Protein function is determined by how the protein folds to form a specific three-dimensional structure. The way that a protein folds is determined by the free energy of the constituent amino acid residues (Levitt et al., 1997). As much as 50% of the primary amino acid sequence is nec- essary just to define the three-dimensional structure of a typical protein (Dobson et al., 1998).