Antibody-antigen complexes are removed from solution by addition of an insoluble form of an antibody binding protein such as Protein A, Protein G or second antibody. Immunoprecipitation protocols / methodology and technical background information. P.J. Ha - [Read Analysis of Proteins by Immunoprecipitation]
Enzyme-linked reagents give excellent sensitivity and use a simple light microscope for detection. A range of enzymes is available, but for staining in situ, horseradish peroxidase will suit most needs. Diaminobenzidine (DAB) is one of the most sensitive substrates for horseradish peroxidase. It yields an intense brown product that is insoluble in both water and alcohol. It can be made more sensitive by adding metal salts such as cobalt or nickel to the substrate solution. - [Read Antibody Addition to Drosophila Specimens and Detection Using Enzyme-Linked Reagents Protocol]
Calcium phosphate forms an insoluble precipitate with DNA, which attaches to the cell surface and is taken into the cells by endocytosis. The protocol is easily adapted for use with other types of cells, both adherent and nonadherent. This protocol is a modified version of a method published by Jordan et al. (1996) who rigorously optimized calcium-phosphate-based transfection methods for Chinese hamster ovary cells and the 293 line of human embryonic kidney cells. - [Read Calcium-phosphate-mediated Transfection of Eukaryotic Cells with Plasmid DNAs]
For cells grown in tissue culture, the most useful method of lysis is treating with detergents, as described in this protocol. Non-ionic detergents, such as NP-40, solubilize the plasma and intracellular membranes, break many weak intermolecular bonds, and solubilize most of the commonly studied protein antigens. RIPA lysis buffer may be used as a more rigorous extraction buffer to release all but the insoluble proteins of the cell and to break most weak noncovalent interactions. - [Read Lysing Tissue-Culture Cells for Immunoprecipitation Protocol]
Protocol describes a nondenaturing immunoprecipitation (IP) for mammalian cells. Prefer to use denaturing IPs to recover labeled proteins from pulse-chase experiments. However, the nondenaturing protocol is useful when one wishes to separate soluble from insoluble proteins, or when the antibody being used recognizes a native epitope. - [Read Nondenaturing Protein Immunoprecipitation from Mammalian Cells Protocol]
Protocol for the isolation of the lipid-rich microdomains of the plasma membrane, notably caveolae and lipid rafts. Methods for the isolation of lipid rafts are based on the insolubility of these structures in the nonionic detergent TritonX-100. Either the intact cells are treated with a detergent-containing solution or a post-nuclear supernatant is prepared from a cell homogenate and then Triton X-100 is added to this supernatant. - [Read S20 Purification of detergent-insoluble lipid rafts from cells and tissues.]
In Vitro Translated Xenopus Mos Kinase Assay Protocol. In response to progesterone, immature Xenopus oocytes mature to eggs that can be fertilized. The Mos protein kinase is essential for oocyte maturation, most likely due to its ability to activate the MAP kinase cascade. This MAP kinase cascade eventually leads to the activation of Cdc2/cyclin B and entry into M phase. In this protocol, tagged Mos kinase is translated in vitro, immunopurified, and used in a kinase assay.