Team:Illinois/Antibody RTK Fusion

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Revision as of 07:59, 12 June 2008

Core Team Members

Aleem, Joleen, Graham, Palak, Yanfen, Matt

Project Abstract

In the diverse world of cellular signalling pathways one of the most studied and well characterized family of receptors are the receptor tyrosine kinases. These cell surface proteins detect a wide range of extracellular ligands including hormones, growth factors, and cytokines. Receptor tyrosine kinases are most typically composed of an extracellular ligand binding domain, a single transmembrane helix, and an intracellular effector domain. Upon receptor binding of its ligand, signal cascades are activated within the cell. The first step in these signal cascades is often receptor oligomerization and cross-phosphorylation which leads to activation of MAP kinase cascades or other pathways. We propose to leverage the well understood mechanisms of receptor tyrosine kinases for the purpose of detecting waterborne diseases.

Specific Plans, Supplies, and Protocols

We have chosen yeast as our platform for this project due to it's ability to correctly express cell surface proteins. Yeast do not naturally produce receptor tyrosine kinases however. Our first step will be to express in yeast a well understood receptor tyrosine kinase, epidermal growth factor receptor for example. From here we will create a fusion protein that will allow us to detect a ligand of our choosing. Our current target is the cholera toxin, for which an antibody against the B subunit of the cholera toxin has been sequenced. A fusion protein containing this antibody in place of EGFR's normal ligand binding domain will bind the cholera toxin, and due to the pentameric structure of the B subunit multiple receptors will be able to oligomerize and thus activate a signal cascade. At this point our goal will be to integrate this signalling event into an endogenous signalling pathway, which we will then engineer to activate transcription of a reporter such as GFP.

To impletment this project we will need to acquire or clone the genes for our receptor tyrosine kinase, the cholera antibody, and other signalling proteins needed to interface with the yeast pathway. Techniques such as PCR, cloning, making fusion proteins, and yeast culture will be needed. Supplies needed will include the cholera B subunit, yeast culture media, and standard molecular biology reagents/kits.

This project can be easily modularized into several subprojects. Expression of the RTK can be carried out independently of ligand binding or signalling, and this could possibly be tested by using fluorescently tagged antibodies to check for cell surface localization of the RTK. The fusion protein could be constructed and antigen binding tested perhaps by FRET or some method of affinity chromatography. The signal cascade could be tested using the unmodified RTK and detecting whether our reporter gene is activated in the presense of the RTK's natural ligand.

Literature References

Crystal Structure at 1.7 Å Resolution of VEGF in Complex with Domain 2 of the Flt-1 Receptor

Function and regulation in MAPK signaling pathways: Lessons learned from the yeast Saccharomyces cerevisiae

Planned Labwork, Procedures, and Results

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