We have isolated and sequenced a gene from petunia (GRP1) which codes for a glycine rich structural protein (67% gly). The carboxyterminal 320 amino acids of the protein sequences can be described by the formula Gly-X-Gly-X, and should form a large b-pleated sheet. GRP1 is only the fourth class of structural proteins to be identified in plants. We have found that GRP1 RNA expression is developmentally regulated and enhanced by wounding. In addition, the predicted amino acid sequence of GRP1 shows that it contains an optimal signal sequence for transport out of the cytoplasm. Our working hypothesis therefore is that the GRP1 gene product functions as a cell wall protein. In this proposal we will determine the possible organ specificity of GRP1 RNA, determine the kinetics of the wound response and determine at what level GRP1 RNA expression is controlled. Using a variety of anti-GRP1 antiboidies raised against synthetic peptide sequences specific to GRP1, we will determine: (1) the subcellular location of the GRP1 gene product, (2) its possible organ and/or cellular specificity and (3) monitor GRP1 protein accumulation in developing or wounded cells. Little is known about the structural proteins of plants. Dr. Carol Condit of the University of Georgia isolated and characterized a gene from petunia which encodes a glycine-rich structural protein. The protein, based upon codon usage, contains 67% glycine and a signal sequence for transport of the cytoplasm. The epxression of the gene is enhanced by wounding. These characteristics strongly suggest that it is a cell wall protein. Dr. Condit proposes to extend these studies by determining the subcellular location of the protein, determining its organ or cellular specifity and monitoring its response to wounding. This work should result in important basic information on plant structural proteins, wound response and mechanisms of transport in plants.
