Binding of murine monoclonal antibodies to the active and inactive configurations of aequorin.
Murine monoclonal IgG1 antibodies (MAb), designated Aq-11 and Aq-12, were prepared against the photoprotein aequorin from jelly fish. Aequorin is a calcium-sensitive photoprotein which consists of a single polypeptide chain, apoaequorin, and a functional chromophore, coelenterazine. Native aequorin consists of two species with molecular masses of 25 and 23.5 kDa. MAb Aq-12 was found by immunoblot analysis to bind specifically to the 25 kDa species, while MAb Aq-11 reacted with the 23.5 kDa protein. Activation of apoaequorin with coelenterazine was associated with a shift of the 23.5 kDa molecule to the 25 kDa species. In contrast, treatment with calcium ions induced a shift back to the 23.5 kDa form. These changes between the active and inactive forms were identified by reactivity with MAbs Aq-11 and Aq-12. The results thus indicate that these MAbs should be useful in monitoring activation of this photoprotein.
Watanabe
M
M
1st Department of Microbiology, Jikei University School of Medicine, Tokyo, Japan.
Kurihara
S
S
Inouye
S
S
Ohno
T
T
D000331:Aequorin / Q000276:immunology*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000941:Antigens / Q000276:immunology; D002118:Calcium / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes / Q000276:immunology; D005260:Female; D015151:Immunoblotting; D008164:Luminescent Proteins / Q000276:immunology*; D051379:Mice; D008970:Molecular Weight; D011487:Protein Conformation
D000911:Antibodies, Monoclonal; D000941:Antigens; D000939:Epitopes; D008164:Luminescent Proteins; D000331:Aequorin; D002118:Calcium