| Abstract | It has been suggested that binding of 11 beta-chloromethyl estradiol (11 beta-CME2) to the estrogen receptor is irreversible, since its complex with receptor fails to undergo exchange with estradiol (E2). To investigate this behavior directly, 11 beta-CME2 was prepared in high specific activity, tritium-labeled form: The binding of [3H]11 beta-CME2 to the estrogen receptor from lamb and rat uterus and MCF-7 human breast cancer cells was shown to be fully reversible; the 11 beta-CME2 complex with receptor, as well as that of a structural analog 11 beta-ethyl estradiol, however, do not dissociate or exchange with [3H]E2 over a 22 h period at 25 degrees C. By competitive or direct binding assays, the affinity of 11 beta-CME2 for the estrogen receptor can be estimated to be as much as 10- to 30-fold higher than that of E2. The complexes of estrogen receptor from MCF-7 cells with [3H]11 beta-CME2 and [3H]E2 show identical velocity sedimentation profiles on sucrose gradients, under conditions when the receptor is either a monomer of a dimer. Because of its very high affinity and unusual dissociation kinetics, [3H]11 beta-CME2 should be a very useful ligand for studies of estrogen receptor dynamics and in the assay of estrogen receptor concentrations in tumors and tissues. |
| Authors | R D Bindal, K E Carlson, G C Reiner, J A Katzenellenbogen
(Affiliation: School of Chemical Sciences, University of Illinois, Urbana 61801.)
|
| Journal | Journal of steroid biochemistry
(J Steroid Biochem)
Vol. 28
Issue 4
Pg. 361-70
(Oct 1987)
ISSN: 0022-4731 ENGLAND |
| PMID | 3669657
(Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)
|
| Chemical References |
- Aziridines
- Estradiol Congeners
- Ketones
- Receptors, Estrogen
- ketononestrol aziridine
- Estradiol
- Dimethylformamide
- 11-beta-chloromethyl-estradiol
|
| Topics |
- Animals
- Aziridines
(metabolism)
- Binding, Competitive
- Breast Neoplasms
(metabolism)
- Cell Line
- Centrifugation, Density Gradient
- Chemistry
- Dimethylformamide
(pharmacology)
- Estradiol
(analogs & derivatives, chemical synthesis, metabolism)
- Estradiol Congeners
- Female
- Humans
- Ketones
(metabolism)
- Kinetics
- Rats
- Receptors, Estrogen
(metabolism)
- Sheep
- Uterus
(metabolism)
|
