| Budget Amount *help |
¥16,920,000 (Direct Cost: ¥15,600,000、Indirect Cost: ¥1,320,000)
Fiscal Year 2007: ¥5,720,000 (Direct Cost: ¥4,400,000、Indirect Cost: ¥1,320,000)
Fiscal Year 2006: ¥4,400,000 (Direct Cost: ¥4,400,000)
Fiscal Year 2005: ¥6,800,000 (Direct Cost: ¥6,800,000)
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| Research Abstract |
A stable complex of a peptide and RNA, ribonucleopeptide (RNP), provides a new framework to construct a macromolecular receptor for small molecules. The RRE RNA and the Rev peptide form a structurally well-characterized stable RNP complex that is suitable for a stepwise functionalization. In vitro selection of the RNP pool originating from an RRE-based RNA library and the Rev peptide affords RNP receptors specific for nucleotide triphosphates or the phosphotyrosine residue. The ligand-binding surface of RNP is further molded in a stepwise manner by using a Rev peptide library. The Rev peptide appended with seven randomized amino acid residues by means of phage display generates a Rev peptide library. An ATP-binding RNP selected from the peptide-based RNP library shows a higher affinity to ATP and a distinct specificity for ATP over dATP as compared to the original ATP-binding RNP.
The RNP receptor functionalized by a fluorophore-labeled Rev peptide exerts optical signals associated with the ligand binding events. Replacing the Rev peptide of the ATP-binding RNP with a fluorophore-modified Rev peptide affords a series of fluorescent ATP sensors. This strategy to generate tailor-made fluorescent sensors is applied for a selective detection of a specific phosphorylated tyrosine residue within a defined amino acid sequence. The phosphotyrosine-binding RNP receptor and fluorescent RNP sensor constructed from the RNP receptor not only discriminate phosphotyrosine against tyrosine, phosphoserine, or phosphothreonine, but also show specific recognition of amino acid residues surrounding the phosphotyrosine residue.
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