Project Summary The study of cellular signaling has benefitted greatly from existing approaches to alter signaling pathways in a controlled manner to delineate specific molecular events that mediate cell function. Mutagenesis is one such method used to remove a specific recognition site, or site of post- translational modification, to evaluate signaling consequences and deduce the importance of the target site. While powerful, this approach requires cell development, growth, and activation to take place in the context of a non-native gene which can have ancillary effects confounding the experimental results. The submitted application takes a completely new approach to the study of cellular signaling; molecularly imprinted nanoparticles (MINPs) have been developed by Yan Zhao that exhibit exquisite selectivity and affinity for their short target sequences. Cell permeability has been demonstrated and in this application Zhao and Andreotti will test the efficacy of these new reagents in the study of T cell signaling. Specific target sequences are chosen for MINP generation, binding affinity and specificity will be tested in vitro and in cell lysates, and internalization and target binding of MINPs in T cells will be fully characterized. If successful, these proof of principle experiments will pave the way for application of MINP technology to every corner of the cell signaling field.