Signal Reception

7 Key excerpts on "Signal Reception"

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  Cell Signaling

  • Wendell A. Lim, Wendell Lim, Bruce Mayer, Tony Pawson(Authors)
  • 2014(Publication Date)
  • Garland Science

    (Publisher)

  Moreover, cells have the ability to monitor aspects of their own internal state, and to respond in a self-correcting way—the foundation of cellular homeostasis and repair. Thus, cell signaling, which encompasses the study of this wide range of stimulus–response behaviors observed in cells, is central to all of biology. Today, as our knowledge of biological systems increases rapidly, we have begun to view cell signaling from the perspective of a more general question: how do cells process information? How a cell receives diverse signaling inputs, processes and integrates these signals, and converts them into responses is in many ways analogous to how other systems, at widely varying scales, process information. We can think about informa-tion processing and storage in the cell, just as we focus on these concepts when we consider a brain or a computer ( Figure 1.1a ). At the level of the organism, for example, we can marvel at the ability of an athlete to detect the movement of a ball, calculate its trajectory, and mount an effective response to intercept it that involves the coordinated action of hundreds of different muscles, all within a fraction of a second. Individual cells per-form similarly remarkable feats, such as detecting the presence of just a few specific molecules in the outside environment, and responding by set-ting in motion elaborate cellular programs that culminate in behaviors such as proliferation, directed migration, or cell death. At each of these scales, a common series of challenges must be overcome. Just a few exam-ples include detecting, amplifying, and robustly responding to a faint incoming signal; integrating and responding coherently to diverse and contradictory signals; and adapting to the strength or duration of a sig-nal and shutting down the response when appropriate. These represent (a) (b) OUTPUTS INPUTS decision-making system Figure 1.1 Cell signaling systems process information.

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  Basic Medical Endocrinology

  • Elizabeth H. Holt, Harry E. Peery(Authors)
  • 2003(Publication Date)
  • Academic Press

    (Publisher)

  The conversion of a hormonal message to cellular responses is called signal transduction and the series of biochemical changes that are set in motion are described as signaling pathways , although in reality signaling network might be a more accurate descriptor, because pathways branch and converge only to branch again. Signal transduction is a complex topic and the focus of intense investigation in many laboratories around the world. Detailed consideration is beyond the scope of this text. Instead, only general patterns of signal transduction are considered in the following section, but the topic will be revisited where appropriate in subsequent chapters in discussing individual hormones. S PECIFICITY Because all hormones travel in blood from their glands of origin to their target tissues, all cells must be exposed to all hormones. Yet under normal circumstances cells respond only to their appropriate hormones. Such specificity of hormone action resides primarily in the ability of receptors in the target cells to recognize only their own signal (Figure 10).We may define a hormone receptor as a molecule or complex of molecules, in or on a cell, that binds its hormone with great selectivity and in so doing is changed in such a manner that a characteristic response or group of responses is initiated. Hormone receptors are a subset of Mechanisms of Hormone Action 19 the huge number of molecules that are utilized by all cells to receive specific information from other cells and the external environment. The mechanisms by which receptors operate and are regulated are not unique to endocrinology. C HARACTERISTICS OF R ECEPTORS Hormone receptors are proteins or glycoproteins that are able to function as follows: 1. They distinguish their hormone from other molecules that may have very similar structures.

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  Lecture Notes

  Human Physiology

  • Ole H. Petersen(Author)
  • 2019(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  Chapter 2 Cellular Communication

  Cells communicate with one another by chemical and electrical signals. There are also specialized sensory cells that respond to chemical, electrical, light, mechanical or heat stimuli that may come from external or internal sources. The cellular response to these signals may be simple and short-lived, such as depolarization, or it may be complex and long-lasting, such as the acquisition of memory. Nevertheless, the cellular mechanisms underlying these responses have much in common. Each of these signals is transduced into electrical or biochemical changes within the cell, which lead to a characteristic response. For example, the stimuli that give rise to the sensations of taste, smell, hearing and vision, and also certain neurotransmitters and hormones, can all control the opening and closing of ion channels and depolarize or hyperpolarize cells.

  In this chapter we discuss how information is transmitted between cells, and how signals from the external and internal environment are received and transduced into electrical and biochemical changes within the cell.

  2.1 How signals are transmitted between cells

  Cells communicate with one another by chemical signals that either diffuse between cells (neurotransmitters, and paracrine and autocrine agents), or are disseminated in the blood (hormones). These signals include small organic molecules (e.g. acetylcholine and adrenaline), and larger molecules such as proteins and steroids. Cells may also communicate with their immediate neighbours through gap junctions, which transmit both electrical and chemical signals.

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  Neurobiology of Psychiatric Disorders

  • Thomas E Schlaepfer, Charles B. Nemeroff(Authors)
  • 2012(Publication Date)
  • Elsevier

    (Publisher)

  Handbook of Clinical Neurology , Vol. 106, No. Suppl (C), 2012

  ISSN: 0072-9752

  doi: 10.1016/B978-0-444-52002-9.00002-4

  Chapter 2 Receptor signaling and the cell biology of synaptic transmission

  Jiang-Zhou Yu, Mark M. Rasenick* E-mail address: [email protected],

  Departments of Physiology and Biophysics and Psychiatry, University of Illinois Chicago College of Medicine, Chicago, IL, USA

  * Correspondence to: Mark M. Rasenick, Distinguished UIC Professor of Physiology and Biophysics and Psychiatry, Director, Biomedical Neuroscience Training Program, University of Illinois Chicago College of Medicine, 835 S. Wolcott m/c 901, Chicago, IL 60612-7342, USA. Tel: 312 996 6641, Fax: 312 996 1414,

  Abstract

  This volume describes a series of psychiatric and neuropsychiatric disorders, connects some aspects of somatic and psychiatric medicine, and describes various current and emerging therapies. The purpose of this chapter is to set the stage for the volume by developing the theoretical basis of synaptic transmission and introducing the various neurotransmitters and their receptors involved in the process. The intent is to provide not only a historical context through which to understand neurotransmitters, but a current contextual basis for understanding neuronal signal transduction and applying this knowledge to facilitate treatment of maladies of the brain and mind.

  Introduction

  Receptors are proteins (either at the cell surface or intracellular) that bind hormone/neurotransmitters and begin the process of converting the agonist from extracellular signal to intracellular response. Generally, receptors recognize a particular hormone/neurotransmitter with great specificity and high affinity. Subsequent to the binding of their agonists, these receptors undergo a change of conformation which shifts them into an activated state.

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  Biology for AP® Courses

  • Julianne Zedalis, John Eggebrecht(Authors)
  • 2018(Publication Date)
  • Openstax

    (Publisher)

  Cells detect and respond to changes in the environment using signaling pathways. Signaling pathways enable organisms to coordinate cellular activities and metabolic processes. Errors in these pathways can cause disease. Signaling cells secrete molecules called ligands that bind to target cells and initiate a chain of events within the target cell. For example, when epinephrine is released, binding to target cells, those cells respond by converting glycogen to glucose. Cell communication can happen over short distances. For example, neurotransmitters are released across a synapse to transfer messages between neurons Figure 1.3. Gap junctions and plasmodesmata allow small molecules, including signaling molecules, to flow between neighboring cells. Cell communication can also happen over long distances using. For example, hormones released from endocrine cells travel to target cells in multiple body systems. How does a ligand such as a hormone traveling through the bloodstream “know” when it has reached its target organ to initiate a cellular response? Nearly all cell signaling pathways involve three stages: reception, signal transduction, and cellular response. Cell signaling pathways begin when the ligand binds to a receptor, a protein that is embedded in the plasma membrane of the target cell or found in the cell cytoplasm. The receptors are very specific, and each ligand is recognized by a different one. This stage of the pathway is called reception. Molecules that are nonpolar, such as steroids, diffuse across the cell membrane and bind to internal receptors. In turn, the receptor-ligand complex moves to the nucleus and interacts with cellular DNA. This changes how a gene is expressed. Polar ligands, on the other hand, interact with membrane receptor protein. Some membrane receptors work by changing conformation so that certain ions, such as Na + and K + , can pass through the plasma membrane.

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  Biochemistry of Vision

  • Hitoshi Shichi(Author)
  • 2012(Publication Date)
  • Academic Press

    (Publisher)

  13 Cellular Receptors and Signal Transmission I. GENERAL MECHANISMS OF SIGNAL TRANSMISSION A variety of extracellular substances affect cellular functions. Some sub-stances bind to cell-surface receptors and exert their effects indirectly on cellular response elements and others do so directly by binding to intracellu-lar receptors (Fig. 1) (/). In the direct mechanism compounds enter the cell and alter cellular functions by interacting with intracellular macromole-cules. Examples are steroid hormones and thyroid hormones, which enter the cells and interact directly with nuclear D N A . In the indirect mechanism, extracellular substances bind to specific receptors located on the cell surface and affect cellular functions indirectly by generating signals or second mes-sengers (e.g., cyclic nucleotides) within the cell. Examples of substances that act by this mechanism include catecholamines, various neurotransmit-ters, glycoprotein hormones (lutropin and thyrotropin), growth hormone (somatotropin), and antigens. In the photoreceptor system, the extracellular agent is light and the light-induced structural change of receptor (visual pigments) triggers a process of signal transmission. The process occurs by 205 206 13. Cellular Receptors and Signal Transmission S7 ^7 Receptor t Cellular function Cellular function Indirect mechanism Direct mechanism Fig. 1. Direct and indirect signal transmission mechanisms. In the indirect mechanism, a signal compound binds to the cell surface receptor and the activated receptor evokes cellular responses through second messengers. In the direct mechanism, a signal compound enters the cell and evokes cellular responses. the indirect mechanism. Light binds to specific photosensitive molecules (photoreceptors) and induces changes in concentrations of second messen-gers that, in turn, modulate membrane permeabilities to ions. Thus, light acts like a hormone that exerts its effect indirectly.

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  Further Milestones in Biochemistry

  • M.G. Ord, L.A. Stocken(Authors)
  • 1997(Publication Date)
  • Elsevier Science

    (Publisher)

  Chapter 6 TALKING TO CELLS-CELL MEMBRANE RECEPTORS AND THEIR MODES OF ACTION Robin F. Irvine Introduction 173 Membrane Receptors 175 Coupling of Receptors to Intracellular Signals 182 Acknowledgments 196 References 196 INTRODUCTION This chapter is essentially about the field of research that we now know as signal transduction or cellular signaling. Currently this field comprises a significant proportion of the world's total research in the life sciences. This is not surprising if one thinks about it. The cells of our tissues are under the constant control of hormones, neurotransmitters, and growth factors, which are telling the cells to do this, do that, stop doing this, do that instead, etc. The great majority of these outside influences—agonists is a useful all-embracing term—are water-soluble. They have to be because they move and work in an aqueous environment. So, when they come up against the hydrophobic cell membrane (plasma membrane) of any cell, they must either be taken up into the cell by an active process (e.g. endocytosis, active transport) which is necessarily slow, or they must bind to a specific recognition site (a receptor) in the plasma membrane, which then registers their presence by sending a chemical signal into the cell. Signal transduction, therefore, is all 173 174 ROBIN F. IRVINE about the nature of these chemical messages, how they are generated after the receptor has bound its ligand (the agonist), and how the cell uses them to alter its function. Because these receptor-generated signals plug-into and modulate the homeostatic control mechanisms of a cell's functions, it is inevitable that in understanding receptor-mediated signal transduction we will understand the fundamentals of cellular function.

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