RAS enzyme-linked immunoblot assay discriminates p21 species: A technique to dissect gene family expression

The members of the RAS gene family of protooncogenes are of implied biological significance in oncogenesis. The precise role of these genes is unclear. One difficulty has been the inability to discriminate the individual p21 protein products of various ras genes in cell lines, de novo human tumors, and related normal tissues. In this report, specific proteins of the human c-Ha ras-1, c-Ki- ras-2, and c-N- ras genes have been detected and discriminated by the differential use of various antisera recognizing these p21s. This enzyme-linked immunoblot assay utilizes a double antibody system in which monoclonal antibodies are initially used to immunoprecipitate the p21 ras proteins. Immunoprecipitates are then subjected to one-dimensional Western blot analysis utilizing other antibodies raised against p21s, coupled with nonradiolabeled enzyme-linked colorimetric detection. By direct detection, the specific products of the three human ras genes can be discriminated. In addition, we describe the generation and characterization of a new anti-p21 c-N- ras -specific antibody. The simultaneous expression into protein of multiple ras genes is unequivocally demonstrated in both homogeneous cell lines and heterogeneous human tissues. This new technique is also applicable for discrimination of the protein products of other gene families.