4_Signal%20transduction

4_Signal%20transduction - Signal transduction in cells All...

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1 All cells receive and respond to signals from their environments. It involves signal molecules, receptors, effector molecules, second messengers, and enzymes. Signal transduction in cells A hypothetic pathway of signal transduction in cells http://www.researchherpathways.com/researchhe rpath/overview/receptors/index.m http://commons.wikimedia.org/wiki/File:Signal_transduction_v1.png
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2 Leukemia (2005) 19, 1729–1738. Signaling via large molecules (proteins) Signaling via small molecules (second messengers) - Neurotransmitters (both) - Hormones (both) - Nitric oxide (local, due to short half life) - Lipids (local, due to short half life) - Growth factors (both) - Cytokines (both) - ECM (local) - Mechanical stresses/strains (local) I. Signals (from local or distant sources) II. Signaling pathways A. Via soluble chemicals - Endocrine (chemicals from distant cells) - Paracrine (chemicals from local cells) - Synaptic (chemicals from adjacent cell) - Autocrine (chemicals from itself) B. Via direct cell-cell interactions - gap junction - cell-cell adhesion C. Via interactions with environment - Mechanical stresses -ECMbinding (1) Extracellular pathways (2) Intracellular pathways (see later)
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3 III. Cell responses A. Mediated by protein synthesis - Metabolisms, - Migration and shape change - Proliferation, - Differentiation. - Apoptosis B. Others (e.g., opening of ligand-gated ion channels ) IV. The first step of signaling A. Binding of signal molecules to their receptors (this is the case in most situations.) - Binding and receptor-mediated endocytosis - Binding without endocytosis - Binding to intracellular receptors B. Others - Direct diffusion of signal molecules into cells (e.g., NO through membrane and other molecules through gap junctions) - Mechanical stress/strain-mediated cell deformation, and conformational changes of receptors or ion channels. • Ligand-gated ion channels: the signal is carried by ion fluxes • G protein-coupled receptors or seven transmembrane receptors ( Robert Lefkowitz ) • Receptor tyrosine kinase: receptors with intrinsic protein kinase activity (e.g., insulin receptor) • Enzyme-linked receptors: receptors associated with enzymes (e.g., receptors-linked with tyrosine kinase or tyrosine phosphatase) Four classes of cell-surface receptors for signal transduction
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4 - Receptor : receive signals from environment.
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4_Signal%20transduction - Signal transduction in cells All...

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