The present invention relates to a method and detection kit for determining a presence of one or more proteins using aptamer-mediated pull-down assays. Specifically, a reproducible a protein precipitation (Co-AP/AP) method is provided to identify physiologically relevant protein-protein interactions by using target protein-specific aptamers, and to confirm its superior performance over antibody based protein precipitation (Co-IP/IP) methods in terms of its protein pull-down performance.