Formaldehyde cross-linking and chromatin immunoprecipitation assays of
tissue culture cells, Based on Boyd and Farnham. Michelle Kallesen, Rosen Lab. - [Read ChIP Assay Protocol PDF]
ChIP assay protocol with 2 steps: in vivo formaldehyde cross-linking of whole cells and protein-protein and protein-DNA interactions, followed by immunoprecipitation of protein-DNA complexes with specific antibodies from sonicated extracts. Breeden Lab - [Read Chromatin IP (CHIP assay)]
Mapping Protein/DNA Interactions by Cross-Linking Examining the Distribution of Telomeric and DNA Repair Proteins by ChrIP and Real-Time PCR - [Read Chromatin-IP (ChrIP) Protocol]
Activation and inactivation of proteins using photoactivation of caged peptides or proteins offer insights into cellular dynamics not achievable using genetic means. The ability to selectively alter the activity of a specific protein at a defined time and location inside a cell allows the correlation of changes in protein activity and cellular behavior. A caged compound, peptide, or protein is prepared by covalently linking it to a photolabile, protecting group. - [Read Introduction of Caged Peptide/Protein into Cells Using Microinjection Protocol]
The multiprotein-DNA complex of interest is formed using the site-specifically derivatized DNA fragment. The complex is then UV-irradiated, initiating covalent cross-linking with proteins in direct physical proximity to the cross-linking agent. Extensive nuclease digestion is performed to eliminate uncross-linked DNA and convert cross-linked DNA to a cross-linked, radiolabeled nucleotide "tag." - [Read Site-Specific Protein-DNA Photo-Cross-Linking: Analysis of Structural Organization of Protein-DNA]