hormone receptor

Examples of hormone receptor in the following topics:

• Hormone Receptors

  • A hormone receptor is a molecule that binds to a specific hormone.
  • Receptors for peptide hormones tend to be found on the plasma membrane of cells, whereas receptors for lipid-soluble hormones are usually found within the cytoplasm.
  • The number of these complexes is in turn regulated by the number of hormone or receptor molecules available, and the binding affinity between hormone and receptor.
  • The receptors for these hormones need to be localized to the cells' plasma membranes.
  • The thyroid hormone receptor (TR) heterodimerized to the RXR.

• Target Cell Specificity

  • Hormones target a limited number of cells (based on the presence of a specific receptor) as they circulate in the bloodstream.
  • This androgen insensitivity occurs when the receptors on the target cells are unable to accept the hormone due to an impairment in receptor shape.
  • Target cells are capable of responding to hormones because they display receptors to which the circulating hormone can bind.
  • For example, after receptor stimulation the signaling target cell often sends feedback to the hormone-secreting tissue to down-regulate hormone expression.
  • In some instances, alterations of receptor structure due to a genetic mutation can lead to a reduction in hormone–receptor affinity, as in the case of androgen insensitivity.

• Plasma Membrane Hormone Receptors

  • Hormones that cannot diffuse through the plasma membrane instead bind to receptors on the cell surface, triggering intracellular events.
  • Lipid-insoluble hormones bind to receptors on the outer surface of the plasma membrane, via plasma membrane hormone receptors.
  • When a hormone binds to its membrane receptor, a G protein that is associated with the receptor is activated.
  • When a hormone is not bound to the receptor, the G protein is inactive and is bound to guanosine diphosphate, or GDP.
  • Describe the events that occur when a hormone binds to a plasma hormone receptor

• Intracellular Hormone Receptors

  • Other lipid-soluble hormones that are not steroid hormones, such as vitamin D and thyroxine, have receptors located in the nucleus.
  • The hormone-receptor complex stimulates transcription of specific genes in the same way that steroid hormones do.
  • Upon hormone binding, the receptor dissociates from the heat shock protein and translocates to the nucleus.
  • In the nucleus, the hormone-receptor complex binds to a DNA sequence called a hormone response element (HRE), which triggers gene transcription and translation.
  • Describe how hormones alter cellular activity by binding to intracellular receptors

• How Hormones Work

  • Hormones are chemical messengers that relay messages to cells that display specific receptors for each hormone and respond to the signal.
  • Hormones mediate changes in target cells by binding to specific hormone receptors.
  • Cells can have many receptors for the same hormone, but often also possess receptors for different types of hormones.
  • Cells respond to a hormone when they express a specific receptor for that hormone.
  • Depending on the location of the protein receptor on the target cell and the chemical structure of the hormone, hormones can mediate changes directly by binding to intracellular hormone receptors and modulating gene transcription, or indirectly by binding to cell surface receptors and stimulating signaling pathways.

• Mechanisms of Hormone Action

  • Hormones activate target cells by diffusing through the plasma membrane of the target cells (lipid-soluble hormones) to bind a receptor protein within the cytoplasm of the cell, or by binding a specific receptor protein in the cell membrane of the target cell (water-soluble proteins).
  • Recognition of the hormone by an associated cell membrane or an intracellular receptor protein.
  • Nuclear hormone receptors are activated by a lipid-soluble hormone such as estrogen, binding to them inside the cell.
  • Lipid-soluble hormones can cross the plasma membrane.
  • Water-soluble hormones, such as epinephrine, bind to a cell-surface localized receptor, initiating a signaling cascade using intracellular second messengers.

• Direct Gene Activation and the Second-Messenger System

  • Hormones can alter cell activity by binding with a receptor.
  • Upon binding to a hormone the receptor and hormone translocate into the nucleus, and bind to specific sequences of DNA known as hormone response elements (HREs).
  • Hormone binding to the nuclear receptor results in dissociation of the co-repressor and the recruitment of co-activator proteins.
  • Most hormone receptors are G protein-coupled receptors.
  • Upon hormone binding, the receptor undergoes a conformational change and exposes a binding site for a G-protein.

• Blocking of Hormone Receptors

  • A receptor antagonist is a type of receptor ligand or drug that does not provoke a biological response itself upon binding to a receptor, but blocks or dampens agonist-mediated responses.
  • Biochemical receptors are large protein molecules that can be activated by the binding of a ligand (such as a hormone or drug).
  • Binding to the active site on the receptor regulates receptor activation directly.
  • The current accepted definition of receptor antagonist is based on the receptor occupancy model.
  • Explain the methods by which antagonists block action by agonists at hormone receptors

• Onset, Duration, and Half-Life of Hormone Activity

  • A hormone's half-life and duration of activity are limited and vary from hormone to hormone.
  • A hormone's half-life and duration of activity are limited and vary from hormone to hormone.
  • The relationship between the biological and plasma half-lives of a substance can be complex, due to factors including their accumulation in tissues, active metabolites, and receptor interactions.
  • The duration of hormone activity refers to the duration of events that were stimulated by hormone-receptor binding.
  • Luteinizing hormone 4.

• Lipid-Derived, Amino Acid-Derived, and Peptide Hormones

  • All hormones in the human body can be divided into lipid-derived, amino acid-derived, and peptide hormones.
  • The primary class of lipid hormones in humans is the steroid hormones.
  • Examples of steroid hormones include estradiol, which is an estrogen, or female sex hormone, and testosterone, which is an androgen, or male sex hormone.
  • These hormones cannot pass through plasma membranes of cells; therefore, their receptors are found on the surface of the target cells.
  • The structures of peptide hormones (a) oxytocin, (b) growth hormone, and (c) follicle-stimulating hormone are shown.