Low Signal from Using N-ChIP for Weak DNA-Binding Proteins
Symptom
Consistently low or absent signal when studying transcription factors or chromatin-associated proteins using native ChIP (N-ChIP). Histone ChIP experiments work well in the same laboratory.
Common Causes
1Target proteins have weak DNA affinity and dissociate during N-ChIP
2Proteins located far from DNA require cross-linking for stabilization
3N-ChIP suitable only for tightly associated proteins like histones
4Lack of formaldehyde cross-linking allows protein-DNA complex dissociation
Solutions
1Use X-ChIP (cross-linked ChIP) for proteins with weaker DNA affinity
2Use X-ChIP for proteins located far from DNA (e.g. chromatin remodelers)
3Cross-link with 1% formaldehyde for 10-15 min before cell lysis
4Reserve N-ChIP exclusively for histones and very tightly bound proteins