Genetically encoded

Cherif F. Matta is about to complete his Ph D. in theoretical/quantum chemistry with Professor Richard F. W. Bader at McMaster University (Canada). He has taught general, physical and quantum chemistry for over five years. His main research interest is in developing new theoretical methods for calculating the properties of large complex molecules from smaller fragments. He applied the new method to obtain accurate properties of several opioids molecules. He is also interested in QSAR of the genetically-encoded amino acids. 

Sakurai, T., Nagata, R Yamanaka, A. et al. (2005). Input of orexin/hypocretin neurons revealed by a genetically encoded tracer in mice. Neuron 46, 297-308. 

Violin, J. D., Zhang, J., Tsien, R. Y. and Newton, A. C. (2003). A genetically encoded fluorescent reporter reveals oscillatory phosphorylation by protein kinase C. J. Cell Biol. 161, 899 909. 

Ting, A. Y., Kain, K. H., Klemke, R. L. and Tsien, R. Y. (2001). Genetically encoded fluorescent reporters of protein tyrosine kinase activities in living cells. Proc. Natl. Acad. Sci. USA 98, 15003-8. 

Fluorescence or Forster resonance energy transfer (FRET) is widely accepted as being one of the most useful methods to observe biochemical events in vitro and in living cells. Generally, there are two forms of FRET sensors those based on a pair of genetically encoded fluorophores, usually employing fluorescent proteins from jellyfish or corals, or those based on small molecules that make use of small organic fluorophores. 

Fluorescence imaging with genetically encoded fluorophores is widely being used to study the dynamics and turnover of diverse proteins involved in different plant signal transduction pathways... 

Looger, L. L., Lalonde, S. and Frommer, W. B. (2005). Genetically encoded FRET sensors for visualizing metabolites with subcellular resolution in living cells. Plant Physiol. 138, 555-7. 

Fehr, M., Takanaga, H., Ehrhardt, D. W. and Frommer, W. B. (2005b). Evidence for high-capacity bidirectional glucose transport across the endoplasmic reticulum membrane by genetically encoded fluorescence resonance energy transfer nanosensors. Mol. Cell. Biol. 25, 11102-12. 

The introduction and diversification of genetically encoded fluorescent proteins (FPs) [1] and the expansion of available biological fluorophores have propelled biomedical fluorescent imaging forward into new era of development [2], Particular excitement surrounds the advances in microscopy, for example, inexpensive time-correlated single photon counting (TCSPC) cards for desktop computers that do away with the need for expensive and complex racks of equipment and compact infrared femtosecond pulse length semiconductor lasers, like the Mai Tai, mode locked titanium sapphire laser from Spectra physics, or the similar Chameleon manufactured by Coherent, Inc., that enable multiphoton excitation. 

The two most established methods of labeling a molecule or pair of molecules to make a FRET measurement are immunolabeling and fusion to genetically encoded FPs like GFP. Although these are well established techniques, they have certain drawbacks and so novel sensors like QDs and labeling techniques, like cysteine-reactive fluorophores continue to be developed and offer great promise for the future. 

Mank M, Griesbeck O (2008) Genetically encoded calcium indicators. Chem Rev 108 1550-1564... 

Umezawa Y (2005) Genetically encoded optical probes for imaging cellular signaling pathways. Biosens Bioelectron 20 2504-11... 

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