期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1977
卷号：74
期号：4
页码：1398-1402
DOI：10.1073/pnas.74.4.1398
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Highly purified alkaline phosphatase [orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1 ] from calf intestine inactivates the glucocorticoid-binding capacity of soluble preparations from mouse fibroblasts (L cells) and rat liver. The unbound receptor is sensitive to inactivation whereas the steroid-bound receptor is unaffected. The ability of the enzyme preparation to inactivate the receptor, like its ability to dephosphorylate p-nitrophenyl phosphate, is dependent on zinc and inhibited by arsenate. Both the dephosphorylating and receptor inactivating activities coelute during DEAE-cellulose purification of the enzyme. There is no detectable proteolytic activity in the purified alkaline phosphatase preparation. In a mixed system containing both glucocorticoid and estrogen receptors, the glucocorticoid receptor is selectively inactivated. Although these observations do not prove that the receptor molecule itself is the substrate, they are consistent with the proposal that the glucocorticoid receptor can be inactivated by dephosphorylation and that only the phosphorylated form of the molecule is capable of binding steroid. A phosphorylation-dephosphorylation mechanism may be responsible for determining the level of active receptor in the cell.
