Wild-type kinase domain of human Ephrin receptor A2 (EPHA2) and crystallization thereof

1. A composition comprising a protein-ligand complex in crystalline form wherein the protein of the complex consists of SEQ ID NO: 3, wherein said protein is in complex with an ATP-binding site ligand, and wherein the protein crystal has a crystal lattice in a P3 2 21 space group and unit cell dimensions, ±5% of a=72.12 Å, b=72.12 Å and c=241.62 Å.

2. A composition according to claim 1 wherein there are two molecules of the protein-ligand complex per asymmetric unit of the crystal.

3. A composition according to claim 1 wherein the crystal diffracts X-rays for a determination of structure coordinates to a resolution higher than 3.0 Angstroms.

4. A method for forming a crystal of a protein-ligand complex comprising: forming a crystallization volume comprising a precipitant solution and a protein-ligand complex, wherein the protein of the complex consists of SEQ ID NO:3 and is in complex with an ATP-binding site ligand, storing the crystallization volume under conditions suitable for crystal formation of the protein-ligand complex such that a crystal of the protein-ligand complex is formed, wherein the crystal has a crystal lattice in a P3 2 21 space group and unit cell dimensions, ±5% of a=72.12 Å, b=72.12 Å and c=241.62 Å.

5. The method according to claim 4 wherein there are two molecules of the protein-ligand complex per asymmetric unit of the crystal.

6. A method according to claim 4 wherein the crystal diffracts X-rays for a determination of structure coordinates to a resolution higher than 3.0 Angstroms.

7. A method according to claim 4 , the method further comprising:

diffracting the protein ligand crystal to produce a diffraction pattern; and

solving the structure of the protein from the diffraction pattern.

8. A method according to claim 7 , the method further comprising:

performing rational drug design using the solved structure; and

identifying an entity that associates with the protein.

9. A method according to claim 8 wherein there are two molecules of the protein-ligand complex per asymmetric unit of the crystal.

10. A method according to claim 8 , the method further comprising:

selecting one or more entities based on the rational drug design; and

contacting the selected entities with the protein.

11. A method according to claim 10 , the method her comprising measuring an activity of the protein when contacted with the one or more entities.

12. A method according to claim 11 , the method further comprising:

comparing activity of the protein in a presence of and in the absence of the one or more entities, and

selecting entities where activity of the protein changes depending whether a particular entity is present.

13. An isolated non-crystalline protein consisting of residues 596-900 of SEQ ID NO: 1.

14. A non-crystalline protein consisting of SEQ ID NO:3.

15. A non-crystalline protein comprising SEQ ID NO: 3.