No Protein Detected: Insufficient Antibody Capture

Symptom

No target protein is detected in the elution fraction after immunoprecipitation procedure is completed. Western blot or other detection methods show no signal for the target protein.

1. 1 Antibody concentration is below the minimum required for effective capture of target protein
2. 2 Insufficient antibody amount used relative to the abundance of target protein in sample
3. 3 Antibody binding capacity exceeded by excess target protein without proportional antibody increase

1. 1 Check vendor datasheet for recommended antibody amount per IP reaction and verify current usage meets minimum
2. 2 Titrate antibody concentration upward in 2-fold increments (e.g., 2 µg, 4 µg, 8 µg) to optimize capture efficiency
3. 3 Calculate antibody:protein molar ratio and adjust antibody amount proportionally to sample protein concentration

Related Video (2)

Cell Signaling Technology ★ 85

Western Blotting Protocol

"Western blotting is the detection method used to check IP elution fractions, so this video shows the readout end of the workflow where 'no protein detected' would be observed."

Cell Signaling Technology ★ 72

How CUT&RUN Profiles Chromatin | Cell Signaling Technology

"CUT&RUN is a chromatin immunoprecipitation-based assay that explicitly covers IP principles and antibody capture context similar to the failed procedure."