title: A cysteine-rich extracellular protein, LAT52, interacts with the extracellular domain of the pollen receptor kinase LePRK2.
abstract: Pollen germination and pollen tube growth are thought to require extracellular cues, but how these cues are perceived and transduced remains largely unknown. Pollen receptor kinases are plausible candidates for this role; they might bind extracellular ligands and thereby mediate cytoplasmic events required for pollen germination and pollen tube growth. To search for pollen-expressed ligands for pollen receptor kinases, we used the extracellular domains of three pollen-specific receptor kinases of tomato (LePRK1, LePRK2, and LePRK3) as baits in a yeast two-hybrid screen. We identified numerous secreted or plasma membrane-bound candidate ligands. One of these, the Cys-rich protein LAT52, was known to be essential during pollen hydration and pollen tube growth. We used in vivo coimmunoprecipitation to demonstrate that LAT52 was capable of forming a complex with LePRK2 in pollen and to show that the extracellular domain of LePRK2 was sufficient for the interaction. Soluble LAT52 can exist in differently sized forms, but only the larger form can interact with LePRK2. We propose that LAT52 might be a ligand for LePRK2.
authors.affiliation: Plant Gene Expression Center, United States Department of Agriculture/Agricultural Research Service, Albany, California 94710, USA.
authors.forename: Weihua
authors.initials: W
authors.lastname: Tang
authors.forename: Inés
authors.initials: I
authors.lastname: Ezcurra
authors.forename: Jorge
authors.initials: J
authors.lastname: Muschietti
authors.forename: Sheila
authors.initials: S
authors.lastname: McCormick
mesh_terms: D001665:Binding Sites / Q000502:physiology; D004492:Edetic Acid / Q000494:pharmacology; D006358:Hot Temperature; D018551:Solanum lycopersicum / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011058:Pollen / Q000201:enzymology* / Q000254:growth & development; D011233:Precipitin Tests; D011485:Protein Binding / Q000187:drug effects; D025941:Protein Interaction Mapping; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D015003:Yeasts / Q000235:genetics
chemical_list: C102694:LAT52 protein, Lycopersicon esculentum; D008565:Membrane Proteins; D010940:Plant Proteins; D011994:Recombinant Proteins; D004492:Edetic Acid; D011494:Protein Kinases; C061570:protein kinase N; D011493:Protein Kinase C