Template-directed assembly of signaling proteins: a novel drug screening and research tool.

A multitude of proteins reside at or near the cell membrane, which provides a unique environment for organizing and promoting assemblies of proteins that are involved in a variety of cellular signaling functions. Many of these proteins and pathways are implicated in disease. For example, strong links have been established between receptor tyrosine kinases and disease, most notably, cancer. However, a significant impediment to researchers remains: membrane-associated proteins are difficult to reconstitute and study. Template-directed assembly represents a powerful new technology that enables the assembly of membrane-associated proteins. We show that template-directed assembly restores tyrosine kinase activity and regulation, and provides a way for researchers to build multicomponent assemblies. As an example of better enzyme regulation, the Tie2 tyrosine kinase domain exhibits (biologically relevant) autoinhibitory behavior when template assembled. Also, template-assembled insulin receptor tyrosine kinase domains exhibit significant autophosphorylation (none detected without template-directed assembly) and an eightfold increase in substrate phosphorylation (compared to best solution conditions). Thus, template-directed assembly has a demonstrated ability to effectively produce more biologically relevant results using these commercial reagents. Template-directed assembly promises to be generally applicable to the signaling networks important for human health, because these pathways frequently contain membrane-associated proteins that require the organizing influence of a membrane surface.