title: Identification and characterization of PiORP1, a Petunia oxysterol-binding-protein related protein involved in receptor-kinase mediated signaling in pollen, and analysis of the ORP gene family in Arabidopsis.
abstract: Oxysterol-binding proteins (OSBPs) and oxysterol-binding-protein related proteins (ORPs) are encoded by most eukaryotic genomes examined to date; however, they have not yet been characterized in plants. Here we report the identification and characterization of PiORP1, an ORP of Petunia inflata that interacts with the cytoplasmic kinase domain of a receptor-like kinase, named PRK1, of P. inflata. PiORP1 is phosphorylated by PRK1 in vitro and therefore may be involved in PRK1 signaling during pollen development and growth. RNA gel blot analysis showed that PiORP1 and PRK1 had very similar expression patterns in developing pollen, mature pollen and pollen tubes. GFP fusion proteins of PiORP1 localized in the plasma membrane of pollen tubes at distinct foci and its PH domain alone was sufficient to mediate this localization. The sequence for the oxysterol-binding domain of PiORP1 was used to search the genome of Arabidopsis; 12 ORPs were identified and phylogenetic analysis revealed that they fell into two distinct clades, consistent with the ORPs of other eukaryotes. RT-PCR analysis showed that all 12 Arabidopsis ORPs were expressed; 10 were expressed in most of the tissues examined under normal growth conditions, but only three were expressed in pollen.
authors.affiliation: Department of Biochemistry and Molecular Biology, 403 Althouse Laboratory, The Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: Andrea L
authors.initials: AL
authors.lastname: Skirpan
authors.forename: Peter E
authors.initials: PE
authors.lastname: Dowd
authors.forename: Paja
authors.initials: P
authors.lastname: Sijacic
authors.forename: Cynthia J
authors.initials: CJ
authors.lastname: Jaworski
authors.forename: Simon
authors.initials: S
authors.lastname: Gilroy
authors.forename: Teh-Hui
authors.initials: TH
authors.lastname: Kao
mesh_terms: D017360:Arabidopsis / Q000235:genetics*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics*; D032306:Petunia / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011058:Pollen / Q000378:metabolism*; D015398:Signal Transduction; D013261:Sterols / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D013261:Sterols