Two proteins that are commonly fused to proteins of interest are green fluorescent protein (GFP) and maltose binding protein (MBP). Alternatively, proteins of interest are fused to a specific peptide sequence rather than an entire protein. This peptide sequence defines an epitope that can be readily detected with a specific antibody. Two commonly used peptide tags are derived from human influenza virus hemagglutinin (HA) and c-Myc.Fusion Protein Purification. The Fusion-Aid™ Kits are designed to immunoprecipitate/isolate fusion proteins containing the appropriate protein tag. The Fusion-Aid™ Kit has affinity-purified primary antibodies coupled directly to agarose beads. In contrast to traditional methods, this eliminates the contamination of the isolated proteins with coprecipitating primary antibodies. The spin columns provided with the kit also facilitate rapid immunoprecipitation and maximum protein recovery.