Receptors, Mechanism of Action and Biological Responses of Hormones in the Fetal, Placental and Maternal Compartments

摘要: This chapter describes steroid hormone receptors as belonging to a superfamily of ligand-activated transcription factors with structural similarities. includes thyroid hormone, vitamin D 3, and retinoic acid receptors. Sequence analysis the has revealed that they are related product v-erb-A oncogene avian erythroblastosis virus c-erb-A proto-oncogene. relationship indicates those molecules may all be part regulatory proteins have arisen over evolutionary time. Binding sites for peptide hormones localized almost exclusively at surface their target cells in plasma membrane fraction. Polypeptide integral transmembrane specific binding site extracellular amino terminus an intracellular domain carboxyl possesses intrinsic tyrosine-kinase activity. Physiological increases endogenous positively regulate but major elevations circulating often cause downregulation luteinizing desensitization cells.