Gfp fusion proteins and their use

Abstract

The present invention provides fusion proteins including a green fluorescent protein inserted into the internal amino acid sequence of a Gαs protein and further provides method of using the fusion protein construct to follow activation of a G-protein receptor by a candidate drug.

1 . A fusion protein comprising a green fluorescent protein inserted into the internal amino acid sequence of a Gαs protein. 
     
     
         2 . The fusion protein of  claim 1 , wherein the insertion is at regions that are free of interactions with receptors or effectors. 
     
     
         3 . The fusion protein of  claim 1  modified for specific receptors by replacing amino acid residues at the C terminal end of Gαs. 
     
     
         4 . A method for making a fusion protein, said method comprising:
 (a) obtaining a molecule having an amino acid sequence of a green fluorescent protein; and   (b) inserting the molecule into the interior of a molecule having an amino acid sequence of a G-protein.   
     
     
         5 . The method of  claim 4  wherein the fusion protein has the amino acid sequence as in SEQ ID NO: 2. 
     
     
         6 . The method of  claim 4 , wherein the G-protein is the Gαs protein. 
     
     
         7 . A method to follow an activation of a G-protein receptor by a candidate drug said method comprising:
 (a) obtaining a G-protein green fluorescent fusion protein;   (b) monitoring fluorescence of the fusion protein in response to the candidate drug; and   (c) inferring from a change in fluorescence whether the drug is an agonist or antagonist.   
     
     
         8 . Use of the fusion protein of  claim 1  to follow the activation of a G-protein receptor. 
     
     
         9 . Use of the fusion protein of  claim 1  to track protein functions in living cells.