Molecular characterization of the gene coding for GPRP, a class of proteins rich in glycine and proline interacting with membranes in Arabidopsis thaliana.

The gene coding for a new class of proteins rich in glycine and proline (GPRP) was cloned in Arabidopsis thaliana. In the protein sequence, five amino acids - glycine, proline, alanine, tyrosine and histidine - account for 79.4% of the total composition. The protein has two different glycine-rich domains interrupted by a hydrophobic segment having a high probability of helix formation. The protein synthesized in vitro interacts with microsomes possibly through the hydrophobic domain. The gene in Arabidopsis has two introns, one in the coding region and the other one in the 5' non-coding region. The later one is 778 bp long. Homologous sequences are found in carrot, tomato and tobacco. GPRP mRNA is found in the different organs of the plant analyzed except in mature seeds and anthers, and mostly in epidermal and vascular tissues. Possible hypotheses about the function of GPRP are discussed.