The present invention relates to a method for preparing transformed plants expressing thyroid stimulating hormone receptor In particular, the present invention relates to a method for preparing transformed plants expressing (hTSHR) or (hTSHR-ECD) which comprises the steps of: (a) transforming plant cells with the following polynucleotide sequences: (i) a polynucleotide sequence encoding hTSHR or hTSHR-ECD; (ii) a promoter that functions in plant cells to cause the production of an RNA molecule operably linked to the polynucleotide sequence of (i); and (iii) a 3'-non-translated region that functions in plant cells to cause the polyadenylation of the 3'-end of said RNA molecule; (b) selecting transformed plant cells; and (c) obtaining transformed plant by regenerating said transformed plant cells, transformed plants and a method for preparing hTSHR or hTSHR-ECD.