Antibodies against synthetic carboxy-terminal peptides distinguish H- ras and K- ras oncogene products p21

Abstract

Synthetic peptides corresponding to the carboxy-terminal region of H- ras, K- ras, and N- ras oncogene product p21 proteins are used to obtain antibodies specific to each ras oncogene product. The synthetic peptides of 32 amino acids are immunogenic in rabbits without being coupled to carriers. Specific antibodies are purified by absorption of the antisera with the other peptides coupled to CH-Sepharose 4B, and antibodies reacting with all three peptides are obtained by affinity chromatography. These findings imply that antibodies specific to each peptide recognize the variable carboxy-terminal region while antibodies reacting with all three peptides recognize the constant region of the carboxy-terminal amino acid sequence of p21 proteins. The affinity-purified antibodies against H- ras and K- ras peptides are shown to react specifically with c-H- ras and v-K- ras p21 proteins expressed in E. coli and eukaryotic cells, respectively. These antibodies may be useful tools to study the functional roles of p21 carboxy-terminal domain and to detect differential expression of the family of ras oncogenes in cancerous tissues. The affinity-purified anti-N- ras peptide antibody, however, fails to react with N- ras p21 in spite of its positive reactivity with the N- ras peptide.