Submitted to: Plant Physiology Plant Gene Register Electronic Submission
Publication Type: Other
Publication Acceptance Date: 12/22/1995
Publication Date: N/A
Citation: Interpretive Summary: GTP-binding proteins are widely distributed among animals, including humans, and plants. They are enzymes that cleave bonds in guanidine triphosphate, thus delivering chemical energy for certain cellular activities. These proteins are critical factors in regulating communication within and between cells, which determines how the cell behaves at a given point in time. Variation within structure of these proteins determines when and where in a cell various cell functions take place. They act as a carrier of information, which they chemically deliver to an appropriate site in the cell. We have characterized the gene coding for a GTP-binding protein in buffelgrass. This protein may be important in the process of asexual reproduction in plants. Further research with this protein may prove useful in developing far superior ways to establish hybrid vigor in new varieties of corn, wheat, and rice.
Technical Abstract: Subtraction library SubA2 was obtained by subtractive hybridization between two cDNA libraries constructed in lambda gt22A from mRNA of apomictic and sexual Pennisetum ciliare inflorescences undergoing meiosis. Duplicate plaque lifts of SubA2 were probed with apomictic and sexual biotinylated mRNA, and inserts that hybridized preferentially with apomictic mRNA were subcloned into Bluescript (+) phagemid vector system. Clone pSUBE (941 bp) contained an open reading frame with a predicted 206 amino acid sequence, an effector loop (YKATIGADF, single letter amino acid code), two phosphate binding sites (GDSGVGKT, DTAG), and two nucleotide binding sites (GNKVD, ETSAK), closely related to cDNAs from tobacco, soybean, and pea. These deduced amino acid sequences are homologous to mammalian Rab7 proteins of the Rab/Ypt subfamily, which contain five conserved functional domains. Included is the YRGA motif, which is specific to Rab/Ypt proteins, and the C-terminal end consisting of two cysteine residues. Terminal CC or CAC distinguishes the Rab/Ypt subfamily from the Ras subfamily. This GTP-binding protein may function during aposporous embryo sac formation.