PMID: 108283Jun 10, 1979

ATP-dependent activation of L cell glucocorticoid receptors to the steroid binding form.

The Journal of Biological Chemistry
J J SandoW B Pratt

Abstract

The specific glucocorticoid binding capacity in cytosols prepared from L929 mouse fibroblasts (L cells) is inactivated with a half-life of approximately 2 h at 25 degrees C. As previously published, this inactivation can be prevented with 10 mM molybdate and markedly slowed by addition of other phosphatase inhibitors such as glucose 1-phosphate and fluoride. We have now found that ATP (5 to 10 mM) also slows the rate of this inactivation. After extensively inactivating the receptor by preincubating cytosol at 25 degrees C for 4 and preventing further inactivation by addition of molybdate, addition of ATP results in reactivation of the steroid binding capacity. Maximal reactivation of 40 to 70% is achieved with 5 to 10 mM ATP. The activation is temperature-dependent and specific for ATP. ADP, GTP, CTP, and UTP do not cause activation and preliminary results indicate no effect of cyclic nucleotides in this system. If activation is prevented by addition of 10 mM EDTA to the cytosol, addition of 3 to 10 mM magnesium permits ATP-dependent activation of the binding capacity. The level of reactivation can be enhanced by addition of a heat-stable factor prepared from the same L cell supernatant. These results support the proposal that ...Continue Reading

Related Concepts

Adenosine Triphosphate, Chromium Ammonium Salt
Metazoa
Cytoplasmic Matrix
Edetic Acid, Sodium Salt
Kinetics
L Cells (Cell Line)
Magnesium
Molybdenum
Glucocorticoid Receptor
Receptors, Steroid

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