Inhibition of yeast adenylate cyclase by antibodies to ras p21.
Monoclonal antibody Y13-259 to ras p21 was shown to bind to the highly conserved residues in the region 63-73 and to neutralize ras action in the Saccharomyces cerevisiae adenylate cyclase system. Inhibition of adenylate cyclase activity in isolated membranes by antibody Y13-259 occurred after a lag period of 6 min. This lag corresponded to the time necessary for binding of antibody Y13-259 to the membranes in a ras-dependent manner. The mechanism of inhibition appeared to be steric in nature because antibody Y13-259 neutralized ras p21 bound to a stable GTP analogue. Monoclonal antibodies Y13-4 and Y13-128 also inhibited yeast adenylate cyclase activity, and the epitopes for both the these antibodies were localized to ras region 65-75. However, the ras residues essential for binding of antibodies Y13-4 and Y13-128 to ras p21 (positions 65, 66, 68 and 75) were different from those essential for binding of antibody Y13-259 (positions 63, 65, 66, 67, 70 and 73). These results indicate that residues 63-75 constitute a major neutralizing epitope on ras p21.
Gibbs
J B
JB
Department of Virus and Cell Biology, Merck, Sharp and Dohme Research Laboratories, West Point, PA 19486.
Marsico-Ahern
J D
JD
Scolnick
E M
EM
Sigal
I S
IS
D000262:Adenylyl Cyclases / Q000276:immunology*; D000911:Antibodies, Monoclonal; D000937:Antigen-Antibody Reactions; D002462:Cell Membrane / Q000201:enzymology / Q000276:immunology; D011232:Chemical Precipitation; D000939:Epitopes / Q000032:analysis; D006150:Guanine Nucleotides / Q000494:pharmacology; D009154:Mutation; D011518:Proto-Oncogene Proteins / Q000276:immunology*; D016283:Proto-Oncogene Proteins p21(ras); D012441:Saccharomyces cerevisiae / Q000201:enzymology*
D000911:Antibodies, Monoclonal; D000939:Epitopes; D006150:Guanine Nucleotides; D011518:Proto-Oncogene Proteins; D016283:Proto-Oncogene Proteins p21(ras); D000262:Adenylyl Cyclases