CLONING AND CHARACTERIZATION OF A CDNA-ENCODING A RAB1-LIKE SMALL GTP-BINDING PROTEIN FROM PETUNIA-HYBRIDA

The cloning of small GTP-binding proteins from Petunia hybrida was per formed using a PCR-based strategy. Degenerate primers were designed fr om the DTAGQE and FMETSA consensus sequences. Three different cDNAs we re amplified. The deduced polypeptide sequences PhPCRGP1 and PhPCRGP2 were homologous to RB11_HUMAN and PhPCRGP3 to RAB1A_HUMAN. Using PhPCR GP3 as a probe, 8 identical clones were selected from a Petunia leaf c DNA library. They all encode the same 22.5 kDa polypeptide, PhRAB1, ab le to bind GTP in vitro and 72% identical to RAB1A_HUMAN. Hybridizable mRNAs encoding PhRAB1 accumulated preferentially in opened flowers.