Method for determining antagonist activity to a cytokinin receptor

Abstract

The present invention provides a method for analyzing agonist-activity to a cytokinin receptor, which comprises (1) bringing an examinee substance into contact with a transformed cell into which DNA coding the cytokinin receptor is introduced and (2) measuring the existence or the quantity of intracellular signal transduction from the cytokinin receptor expressed in the transformed cell, and, a method for analyzing antagonist-activity to a cytokinin receptor, which comprises (1) bringing an examinee substance and a substance having agonist-activity to the cytokinin receptor into contact with a transformed cell into which DNA coding the cytokinin receptor is introduced.

1 . A cytokinin receptor selected from the group consisting of:
 (a) a cytokinin receptor comprising the amino acid sequence of SEQ ID NO: 6;   (b) a cytokinin receptor comprising the amino acid sequence of SEQ ID NO: 2;   (c) a cytokinin receptor comprising the amino acid sequence of SEQ ID NO: 4;   (d) a cytokinin receptor comprising the amino acid sequence of amino acids 196 to 1176 of SEQ ID NO: 2;   (e) a cytokinin receptor comprising the amino acid sequence of amino acids 50 to 1176 of SEQ ID NO: 2;   (f) a cytokinin receptor comprising the amino acid sequence of amino acids 32 to 1036 of SEQ ID NO: 4;   (g) a chimera-type cytokinin receptor comprising extracellular regions, transmembrane regions and histidine kinase regions, all of which are obtained from the same cytokinin receptor selected from the group consisting of CRE 1, AHK2 and AHK3, and receiver regions which are obtained from the histidine kinase encoded by the gene selected from the group consisting of S1n1 gene of budding yeast, Chey gene of Salmonella, RcsC gene of  E. coli  and Phks gene of fission yeast; and   (h) a cytokinin receptor comprising an amino acid sequence that has 95% or higher identity to the amino acid sequence of (a), (b), (c), (d), (e), or (f), wherein said cytokinin receptor has cytokinin receptor activity.   
     
     
         2 . DNA encoding the cytokin receptor of  claim 1 . 
     
     
         3 . A transformed cell into which DNA of  claim 2  has been introduced.