PpRab1, a Rab GTPase from maritime pine is differentially expressed during embryogenesis.
Rab-related small GTP-binding proteins are known to be involved in the regulation of the vesicular transport system in eukaryotic cells. We report the characterization of a previously isolated full-length cDNA PpRab1 from Pinus pinaster. Amino acid sequence analysis revealed the presence of G1-G5 conserved domains of the GTPase Ras superfamily and a double cysteine motif in the C-terminal, characteristic of Rab proteins. The PpRab1 protein shows high sequence similarity to several Rab1 GTP-binding proteins in plants. Phylogenetic analysis showed that, within the Ras superfamily, PpRab1 is more closely related to the Rab family and within this, PpRab1 protein was found to cluster with Arabidopsis subfamily AtRABE, whose members are known to regulate ER-to-Golgi membrane trafficking steps. PpRab1 transcripts were expressed at constitutively high levels for the initial stages of zygotic embryo development, and then their relative abundance decreased as embryo matures. The PpRab1 transcript is not embryo-specific as it was found in roots, cotyledons and hypocotyls. An increase in PpRab1 expression level was observed when seeds are germinated and collected at successive time points of development. In situ RT-PCR analysis revealed an expression signal in early zygotic embryos. In view of the proposed roles of Rab1 GTP-binding protein, the possible function of the protein encoded by PpRab1 in embryogenesis is discussed.
Gonçalves
Sónia
S
Forest Biotech Lab, Instituto de Biologia Experimental e Tecnológica (IBET)/Instituto de Tecnologia Química e Biológica (ITQB), Quinta do Marquês, 2784-505 Oeiras, Portugal.
Cairney
John
J
Rodríguez
María Pérez
MP
Cánovas
Francisco
F
Oliveira
Margarida
M
Miguel
Célia
C
D000595:Amino Acid Sequence; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D006056:Golgi Apparatus / Q000378:metabolism; D008969:Molecular Sequence Data; D028223:Pinus / Q000196:embryology / Q000235:genetics* / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D020691:rab GTP-Binding Proteins / Q000235:genetics*
D017931:DNA Primers; D018744:DNA, Plant; D010940:Plant Proteins; D020691:rab GTP-Binding Proteins