Methods of identifying substances that interact with JTT-1 protein
Novel cell surface molecules recognized by monoclonal antibodies against a cell surface molecule of lymphocytic cells that play an important role in autoimmune diseases and allergic diseases have been isolated, identified, and analyzed for their functions. The cell surface molecules are expressed specifically in thymocytes, lymphocytes activated by ConA-stimulation, and peripheral blood lymphocytes, and induce cell adhesion. Antibodies against the cell surface molecules significantly ameliorate pathological conditions of autoimmune diseases and allergic diseases.
1. A method of identifying a substance that interacts with a polypeptide, the method comprising:
providing a purified polypeptide comprising (a) an extracellular region of the polypeptide set forth in SEQ ID NO:2, or (b) an extracellular region of a polypeptide that consists of the amino acid sequence of SEQ ID NO:2 in which one to ten amino acid residues are substituted, deleted or added, wherein the polypeptide comprises the amino acid sequence Phe-Asp-Pro-Pro-Pro-Phe (SEQ ID NO:21) and inhibits the activation of lymphocytes;
contacting the polypeptide with a test substance; and
determining whether the test substance interacts with the polypeptide.
2. The method of claim 1 , wherein the polypeptide is a fusion protein.
3. The method of claim 2 , wherein the fusion protein comprises a portion of a constant region of an immunoglobulin heavy chain.
4. The method of claim 1 , wherein the polypeptide comprises amino acid residues 1-140 of SEQ ID NO:2.
5. The method of claim 1 , wherein the test substance is a low molecular weight compound.
6. The method of claim 1 , wherein the test substance is a polypeptide.
7. The method of claim 1 , wherein the test substance is an antibody.
8. The method of claim 1 , wherein the polypeptide comprises the amino acid sequence of SEQ ID NO:2.
9. The method of claim 8 , wherein the polypeptide consists of the amino acid sequence of SEQ ID NO:2.
10. The method of claim 9 , wherein the test substance is a low molecular weight compound.
11. The method of claim 1 , wherein the polypeptide comprises the amino acid sequence of SEQ ID NO:2 in which one to ten amino acids are substituted, deleted or added, and wherein
(a) the polypeptide comprises the amino acid sequence Phe-Asp-Pro-Pro-Pro-Phe (SEQ ID NO:21) in its extracellular region,
(b) the polypeptide comprises the amino acid sequence Tyr-Met-Phe-Met (SEQ ID NO:22) in its cytoplasmic region, and
(c) an antibody reactive with the polypeptide induces proliferation of peripheral blood lymphocytes in the presence of an antibody reactive with CD3.
12. The method of claim 11 , wherein the test substance is a low molecular weight compound.