The Xenopus oocyte/mRNA injection system has provided a critical key to the characterization and cloning of cDNAs for various animal neurotransmitter receptors. Dr. Sutton proposes that this system can be used in an analogous manner for the study of plant hormone (phytohormone) receptors. The specific aim of this proposal is to test the hypothesis that plant mRNA injected into Xenopus oocytes will result in the synthesis and incorporation of phytohormone receptors into the Xenopus oocyte plasma membrane, and that these receptors will couple to the Xenopus oocyte second messenger systems. RNA will be isolated from the barley aleurone layer which is known to be responsive to various phytohormones. The RNA will be injected into Xenopus oocytes and the oocytes allowed to incubate for 3-5 days. The successful synthesis and incorporation of the receptors into the oocyte membrane will be tested by monitoring for phytohormone-induced chloride currents in the membrane of the oocytes by the two-electrode voltage clamp technique and by radio-labelled hormone binding studies. If this approach is successful, the results of this research will facilitate the cloning and characterization of plant hormone receptors which have proven elusive to more traditional biochemical approaches. The expression or lack of expression of plant hormone receptors in this animal cell system should also provide significant information about protein sorting to the plasma membrane.
