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Magn Reson Med. 2012 Dec;68(6):1919-23. doi: 10.1002/mrm.24483. Epub 2012 Sep 28.

MRI biosensor for protein kinase A encoded by a single synthetic gene.

Author information

1
Russell H. Morgan Department of Radiology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21231, USA.

Abstract

PURPOSE:

Protein kinases including protein kinase A (PKA) underlie myriad important signaling pathways. The ability to monitor kinase activity in vivo and in real-time with high spatial resolution in genetically specified cellular populations is a yet unmet need, crucial for understanding complex biological systems as well as for preclinical development and screening of novel therapeutics.

METHODS:

Using the hypothesis that the natural recognition sequences of protein kinases may be detected using chemical exchange saturation transfer magnetic resonance imaging, we designed a genetically encoded biosensor composed of eight tandem repeats of the peptide LRRASLG, a natural target of PKA.

RESULTS:

This sensor displays a measurable change in chemical exchange saturation transfer signal following phosphorylation by PKA. The natural PKA substrate LRRASLG exhibits a chemical exchange saturation transfer-magnetic resonance imaging contrast at +1.8 and +3.6 ppm, with a >50% change after phosphorylation with minutes-scale temporal resolution. Expression of a synthetic gene encoding eight monomers of LRRASLG yielded two peaks at these chemical exchange saturation transfer frequencies.

CONCLUSION:

Taken together, these results suggest that this gene may be used to assay PKA levels in a biologically relevant system. Importantly, the design strategy used for this specific sensor may be adapted for a host of clinically interesting protein kinases.

PMID:
23023588
PMCID:
PMC3504643
DOI:
10.1002/mrm.24483
[Indexed for MEDLINE]
Free PMC Article

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