Bivalent binding molecules of 7 transmembrane G protein-coupled receptors
Described herein are methods for identifying and preparing bivalent binding molecules to 7 transmembrane G protein-coupled receptors. The methods disclosed herein are based on the SELEX method for generating high affinity nucleic acid ligands. SELEX is an acronym for Systematic Evolution of Ligands by EXponential enrichment. The methods of this invention combine two or more binding domains to two or more different epitopes of the same 7 transmembrane G protein-coupled receptor. These bivalent binding molecules are useful as therapeutic and diagnostic agents.
1. A bivalent binding molecule to a 7 transmembrane G protein-coupled receptor, wherein said bivalent binding molecule comprises an aptamer to a first epitope coupled to a non-aptamer binding domain which binds to a second epitope of the same receptor, wherein the bivalent binding molecule is identified according to a method comprising:
a) preparing a blended candidate mixture of bivalent binding molecules comprising a candidate mixture of nucleic acid sequences coupled to a non-aptamer binding domain which binds to said second epitope of the receptor;
b) contacting said 7 transmembrane G protein-coupled receptor with said blended candidate mixture of bivalent binding molecules, wherein bivalent binding molecules having an increased affinity to the 7 transmembrane G protein-coupled receptor relative to the blended candidate mixture may be partitioned from the remainder of the candidate mixture;
c) partitioning the increased affinity bivalent binding molecules from the remainder of the blended candidate mixture; and
d) amplifying the increased affinity bivalent binding molecules to yield an enriched mixture of bivalent binding molecules, whereby bivalent binding molecules to a 7 transmembrane G protein-coupled receptor may be identified.
2. The bivalent binding molecule of claim 1 wherein the binding domains are coupled to each other via a linker.
3. The bivalent binding molecule of claim 2 wherein said linker is selected from the group consisting of polyethylene glycol, polypropylene glycol, polyvinyl alcohol, hydrocarbons, polyacrylates and amino-, hydroxy-, thio or carboxy-functionalized silicones, proteins, peptides, polynucleotides, monosaccharides, oligosaccharides, cyclodextrins, dextran and liposomes.
4. The bivalent binding molecule of claim 1 wherein the aptamer binding domain is coupled at the 3′ end to another binding domain.
5. The bivalent binding molecule of claim 1 , wherein said 3 transmembrane G protein-coupled receptor is selected from the group consisting of adenosine, adrenergic, calcium, dopamine, histamine, muscarinic, opioid, and peptide receptors.