Inhibition of dexamethasone binding to human glucocorticoid receptor by New World primate cell extracts

David D. Brandon, John W. Kendall, Kristina Alman, Paula Tower, D. Lynn Loriaux

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

To determine if New World primates express an inhibitor that influences glucocorticoid receptor (GR) binding characteristics, we examined [3H] dexamethasone binding in cytosol prepared from B95-8 lymphoid cells, derived from the cotton top tamarin (Saguinus oedipus), in combination with cytosol prepared from human or rat tissues. B95-8 cytosol inhibited specific binding of [3H]dexamethasone (P < 0.01) when mixed with cytosol prepared from either a human lymphoid cell line (HL) or rat thymus. The inhibitory activity was heat labile and trypsin sensitive. Peak inhibitory activity was found in the 150-200 kd fractions after Sephacryl G-200 ultrafiltration. Scatchard analysis of [3H]dexamethasone binding using mixed cytosol showed a diminished GR apparent binding affinity when compared to HL cytosol. Kinetic studies using mixed cytosol indicated that B95-8 cytosol did not affect the apparent dissociation rate of [3H] dexamethasone. These data demonstrate that B95-8 cells contain a competitive inhibitor that prevents binding of dexamethasone to its cognate receptor.

Original languageEnglish (US)
Pages (from-to)463-466
Number of pages4
JournalSteroids
Volume60
Issue number7
DOIs
StatePublished - Jul 1995

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Endocrinology
  • Pharmacology
  • Clinical Biochemistry
  • Organic Chemistry

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