Aptamer-Directed Protein-Specific Multiple Modifications of Membrane Glycoproteins on Living Cells

Understanding how a cell membrane protein functions on living cells remains a challenge for cell biology. Specific placement of functional molecules on specific proteins in their native environment would allow comprehensive study of proteins' dynamic functions. Existing methods cannot facilely achieve multiple modifications on specific membrane proteins. In this report, we describe an aptamer-induced, protein-specific bio-orthogonal modification technology for precise nongenetic immobilization of multiple small functional molecules on target membrane glycoproteins by combining metabolic technology and aptamer targeting. In brief, DNA probes were designed by modifying aptamers, which bind to target proteins on the surfaces of living cells pretreated with N-azidoacetylmannosamine-tetraacy-lated (Ac(4)ManNAz). The cyclooctynes tagged of DNA probes will approach the azide groups to trigger the bio-orthogonal reactions. After UV irradiation and hybridization with cDNA (complementary DNA), the aptamers can be removed, and the process can be repeated to achieve multiple modifications for multicolor imaging and cell surface nanoengineering on specific proteins.