Development of a competitive enzyme immunoassay for detection of capacity of chemicals to bind quail estrogen receptor α and β

Abstract

In vitro binding assays are useful in the initial screening of endocrine disrupting chemicals. Such assays should be applied to the estrogen receptors (ER) of not only humans but also wildlife. As a system for birds is yet to established, we expressed the ligand binding domain (LBD) of quail ERα and ERβ as a fusion protein with glutathione S-transferase and using these proteins, developed two systems (a competitive enzyme immunoassay and a fluorescence polarization assay) for assaying the capacity to bind ERs in vitro. Moreover, 20 test chemicals selected by Ministry of the Environment of Japan were evaluated in terms of binding ability. Both systems worked well, the competitive enzyme immunoassay proving especially powerful, since it needs no special equipment. This system is applicable to other species including fish, amphibians and reptiles when information on the LBD of ER is available.