Regulation of transcriptional activity

The mechanism for steroid receptor-mediated regulation of target genes involves specific transactivation domains referred to as activation functions, the number of which varies depending on the particular steroid receptor. The availability of the activation domains is modulated by conformational changes induced by steroids and their analogues. In general, agonists induce changes in receptor structure that promote interactions with coactivators, thereby increasing transcription. On the other hand, some agonists and some antagonists induce changes in recep tor structure that facilitate receptor interactions with compressors, thus inhibiting transcription.1-10-1 However, antagonists generally inhibit transcriptional activity by occupying the receptor, thus preventing the steroid from binding.1-7-1


Cholesterol is the precursor for the steroid hormone family, which can be divided into six classes. The members of each class are similar structurally and in their mechanism of action. Steroids are responsible for regulating numerous processes within the body that are necessary for normal biological function.


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4. Niswender, G.D. Molecular control of luteal secretion of progesterone. Reproduction 2002, 123 (3), 333 339.

5. Tsai, M.J.; O'Malley, B.W. Molecular mechanisms of action of steroid/thyroid receptor superfamily members. Annu. Rev. Biochem. 1994, 63, 451 486.

6. Beato, M.; Herrlich, P.; Schutz, G. Steroid hormone receptors: Many actors in search of a plot. Cell 1995, 83 (6), 851 857.

7. Senger, P.L. Regulation of Reproduction Nerves, Hor mones and Target Tissues. In Pathways to Pregnancy and

Parturition; Current Conceptions, Inc.: Pullman, WA, 1998; 78 98. NY.

8. Razandi, M.; Pedram, A.; Greene, G.L.; Levin, E.R. Cell membrane and nuclear estrogen receptors (ERs) originate from a single transcript: Studies of ERalpha and ERbeta expressed in Chinese hamster ovary cells. Mol. Endocrinol. 1999, 13 (2), 307 319.

9. Falkenstein, E.; Heck, M.; Gerdes, D.; Grube, D.; Christ, M.; Weigel, M.; Buddhikot, M.; Meizel, S.; Wehling, M. Specific progesterone binding to a membrane protein and related nongenomic effects on Ca2+ fluxes in sperm. Endocrinology 1999, 140 (12), 5999 6002.

10. Conneely, O.M. Perspective: Female steroid hormone action. Endocrinology 2001, 142 (6), 2194 2199.

11. Auger, A.P. Ligand independent activation of progestin receptors: Relevance for female sexual behaviour. Repro duction 2001, 122 (6), 847 855.

Harold F. Hintz

Cornell University, Ithaca, New York, U.S.A.

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