ISOLATION AND CHARACTERIZATION OF AN AUXIN-BINDING PROTEIN GENE FROM RADISH, AND ITS EXPRESSION IN INSECT CELLS

Auxin-binding protein (ABP1) is a putative receptor for auxin in the p lasma membrane. We isolated a full-length cDNA encoding ABP1 from radi sh by screening a cDNA library with its partial cDNA fragment generate d by the reverse transcriptase-polymerase chain reaction (RT-PCR) meth od. Radish abp1 mRNA was highly expressed in cotyledons, hooks and hyp ocotyls, and less so in roots of radish seedlings. The deduced amino a cid sequence of radish abp1 consisted of conserved auxin-binding motif s, a signal peptide and ER-retention signal, and contained two potenti ally N-linked glycosylation signals. To analyze the biochemical proper ties of the radish abp1 product, this cDNA was expressed in insect cel ls by the baculovirus vector system. The result of tunicamycin-treatme nt showed that the signal peptide was cleaved and that the radish abp1 product was glycosylated at both target sites in insect cells.