Low IP Efficiency from Suboptimal IgG-Bead Binding (Immunoprecipitation (CST Guide))

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IP shows weak target protein recovery despite adequate antibody concentration and protein expression. Bead pellet appears smaller than expected or shows poor antibody capture. Common causes: 1) Protein A beads used with mouse antibody (lower affinity for mouse IgG) 2) Protein G beads used with rabbit antibody (lower affinity for rabbit IgG) 3) Mismatch between bead type and antibody host species reduces capture efficiency Solutions: 1) Use Protein A beads when working with rabbit antibodies (higher affinity for rabbit IgG) 2) Use Protein G beads when working with mouse antibodies (higher affinity for mouse IgG) 3) Consider combination Protein A/G beads to increase IgG binding across species 4) Optimize bead choice according to host species of IP antibody