Immunoprecipitation is a technique in which an antigen is isolated by binding to a specific antibody attached to a sedimentable matrix. It is also used to analyze protein fractions separated by other techniques such as gel filtration or density gradient sedimentation. The source of antigen for immunoprecipitation can be unlabeled cells or tissues, metabolically or intrinsically labeled cells, or in vitro-translated proteins. This unit describes a wide range of immunoprecipitation techniques, using either suspension or adherent cells lysed by various means.Usually, plasmas transfected cells or natural cells are ideal sample for immunoprecipitation.
HepG2 is a immortal cell line consisting of human liver carcinoma cells, isolated from the liver tissue of a 15-year-old Caucasian male who had a well-differentiated hepatocellular carcinoma. Hepatocellular carcinoma is, worldwide, the fifth most-common cancer. The morphology of HepG2 cells is epithelial and they have 55 chromosome pairs. HepG2 cells can be cultured successfully at a large scale, and secret many plasma proteins, such as transferring, fibrinogen, plasminogen and albumin. They can also be stimulated with human growth hormone. HepG2 are adherent, epithelial-like cells growing as monolayers and in small aggregates. Not tumorigenic in immunocompromised mice. The HepG2 cells usually were used to produce liver cancer related proteins. Plasmatics were transfected into the cells,after culturing several days purify the proteins.