High throughput assay using fusion proteins
First Claim
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1. A method of screening for compounds capable of binding to a fusion protein, which is defined as an FK506-binding protein linked to a target protein through a peptide linker, which -comprises the steps of:
- a) mixing a test compound, a tagged- ligand for the target protein, which is selected from a biotinylated ligand or an epitope-tagged ligand, the fusion protein, a radiolabeled ligand selected from 3 H!- or 125 I!-labeled F506 analog and a coated microscintillation plate selected from a streptavidin-coated or anti-antibody coated or protein A-coated microscintillation plates;
b) incubating the mixture from between about 1 hour to about 24 hours;
c) measuring the plate-bound counts attributable to the binding of the tagged ligand to, the fusion protein in the presence of the test compound using scintillation counting; and
d) determining the binding of the tagged ligand to the fusion protein in the presence of the test compound relative to a control assay run in the absence of the test compound.
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Abstract
This application describes a high throughput assay for screening for compounds capable of binding to a fusion protein which consists of a target protein and an FK506-binding protein. The method for preparing the DNA encoding for the fusion protein and for expressing that DNA is also described in the application. The invention also discloses the recombinant DNA and protein sequences for several fusion proteins.
32 Citations
42 Claims
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1. A method of screening for compounds capable of binding to a fusion protein, which is defined as an FK506-binding protein linked to a target protein through a peptide linker, which -comprises the steps of:
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a) mixing a test compound, a tagged- ligand for the target protein, which is selected from a biotinylated ligand or an epitope-tagged ligand, the fusion protein, a radiolabeled ligand selected from 3 H!- or 125 I!-labeled F506 analog and a coated microscintillation plate selected from a streptavidin-coated or anti-antibody coated or protein A-coated microscintillation plates; b) incubating the mixture from between about 1 hour to about 24 hours; c) measuring the plate-bound counts attributable to the binding of the tagged ligand to, the fusion protein in the presence of the test compound using scintillation counting; and d) determining the binding of the tagged ligand to the fusion protein in the presence of the test compound relative to a control assay run in the absence of the test compound. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A process for preparing a recombinant DNA expression vector encoding for a fusion protein, which is defied as an FK506-binding protein linked to a target protein through a peptide linker, comprising the steps of:
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a) removing the stop codon on DNA encoding for the FK506-binding protein; b) synthesizing a modified DNA fragment on the DNA encoding for the FK506-binding protein which encodes for a peptide linker; c) digesting an expression vector at cloning sites; d) cloning the modified DNA fragment encoding for the FK506-binding protein with a peptide linker into the digested expression vector to generate a recombinant DNA expression vector encoding for FK506-binding protein with a peptide linker; and e) cloning DNA -encoding for a target protein into a recombinant DNA expression vector encoding for FK506-binding protein with a peptide linker to produce the recombinant DNA expression vector encoding for the fusion protein. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. Isolated DNA encoding for a fusion protein comprising the sequence:
(SEQ. ID. NO.
1).
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21. Isolated DNA encoding for a fusion protein comprising the sequence:
(SEQ. ID. NO.
2).
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22. Isolated DNA encoding for a fusion protein comprising the sequence:
(SEQ. ID. NO.
3).
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23. A FKBP-ZAP:
- SH2 fusion protein comprising the sequence;
(SEQ. ID. NO.
4).
- SH2 fusion protein comprising the sequence;
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24. A FKBP-SYK:
- SH2 fusion protein comprising the sequence;
(SEQ. ID. NO.
5).
- SH2 fusion protein comprising the sequence;
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25. A FKBP-LCK:
- SH2 fusion protein comprising the sequence;
(SEQ. ID. NO.
6).
- SH2 fusion protein comprising the sequence;
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26. A process for expressing recombinant DNA encoding for a fusion protein, which is defined as a-FK506-binding protein linked to a target protein through a peptide linker in an expression vector comprising the steps of;
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a) transforming a host cell with the fusion protein expression vector; b) inducing expression of the fusion protein in the host cell; c) recovering the fusion protein from the host cell; and d) purifying the fusion protein. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. The process for purifying an isolated FKBP-SH2 fusion protein comprising the steps of:
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a) preparing an affinity matrix consisting of biotinylated phosphopeptide coupled to avidin or streptavidin immobilized on a solid support; b) preparing a freeze/thaw extract from cells expressing the fusion protein; c) loading the extract onto the affinity matrix and washing off unbound protein; and d) eluting the desired fusion protein with phenyl phosphate.
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38. A recombinant FKBP-SH2 domain T7 RNA polymerase-based expression vector, wherein the DNA encodes for the FKBP-ZAP:
- SH2 fusion protein and has the DNA sequence (SEQ. ID. NO.1).
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39. A recombinant FKBP-SH2 domain T7 RNA polymerase-based expression vector, wherein the DNA encodes for the FKBP-SYK:
- SH2 fusion protein and has the DNA sequence (SEQ. ID. NO.
2).
- SH2 fusion protein and has the DNA sequence (SEQ. ID. NO.
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40. A recombinant FKBP-SH2 domain T7 RNA polymerase-based expression vector, wherein the DNA encodes for the FKBP-LCK:
- SH2 fusion protein and has the DNA sequence (SEQ. ID. NO.3).
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41. A recombinant host cell containing the recombinant FKBP-SH2 domain T7 RNA polymerase-based expression vector wherein the recombinant host cell is selected from the group consisting of:
- E. coli BL21 (DE3), E. coli Nova Blue (DE3), and E. coli JM109 (DE3).
- View Dependent Claims (42)
Specification