Hormone-dependent phosphorylation of the glucocorticoid receptor occurs mainly in the amino-terminal transactivation domain
Phosphorylation of glucocorticoid receptors is increased by hormone binding and has been implicated in transcriptional regulation. We performed a phosphoamino acid analysis and identified the phosphorylated regions of the glucocorticoid receptor with respect to its functional domains before and afte...
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Published in | The Journal of biological chemistry Vol. 265; no. 10; pp. 5403 - 5408 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
Bethesda, MD
American Society for Biochemistry and Molecular Biology
05.04.1990
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Subjects | |
Online Access | Get full text |
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Summary: | Phosphorylation of glucocorticoid receptors is increased by hormone binding and has been implicated in transcriptional regulation.
We performed a phosphoamino acid analysis and identified the phosphorylated regions of the glucocorticoid receptor with respect
to its functional domains before and after hormone activation. Receptor was isolated by immunoprecipitation from [32P]orthophosphate-labeled
FTO 2B rat hepatoma cells grown in the absence or presence of glucocorticoids. The receptor contained mainly phosphoserine,
with little phosphothreonine and no phosphotyrosine. Partial proteolysis of receptor from hormone-treated or control cells
revealed a similar phosphopeptide pattern. Chemical cleavage with hydroxylamine and cyanogen bromide or digestion with trypsin
and chymotrypsin localized the majority of receptor phosphorylation sites to a transactivation domain amino-terminal of the
DNA-binding domain. Phosphorylation of this region, termed tau 1/enh2, was increased 2-3-fold by hormone treatment. The DNA-binding
domain itself is weakly phosphorylated; no phosphorylation was found in the hormone-binding domain. Phosphorylated regions
were also identified in receptor deletion mutants stably transfected into CV-1 monkey kidney cells. Hormone-independent phosphorylation
was observed with a strong constitutively active mutant lacking the hormone-binding domain. No phosphorylation was detected
in a mutant lacking the amino-terminal region, which showed only weak, hormone-dependent activity. These results support the
idea that phosphorylation is important for the strength of the glucocorticoid receptor as a transcriptional regulator. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0021-9258 1083-351X |
DOI: | 10.1016/S0021-9258(19)39373-1 |