清华大学：《分子生物学》（英文版）Chapter 26 Signal transduction

Chapter 26 Signal transduction 莘大

Chapter 26 Signal transduction

26.1 Introduction 26.2 Carriers and channels form water soluble paths through the membrane 26.3 Ion channels are selective 26.4 Neurotransmitters control channel activity 26.5 G proteins may activate or inhibit target proteins 266G proteins function by dissociation of the trimer 26. 7 Growth factor receptors are protein kinases 26. 8 Receptors are activated by dimerization 26.9 Receptor kinases activate signal transduction pathways 26.10 The Ras/MAPK pathway 26.11 The activation of Ras 26 12 Activating MAP kinase pathways 26. 13 What determines specificity in signaling 26 14 Cyclic AMP and activation of CreB 26. 15 The JAK-Stat pathway 26. 16TGFb signals through Smads 26.17 Structural subunits can be messengers 消当

26.1 Introduction 26.2 Carriers and channels form water soluble paths through the membrane 26.3 Ion channels are selective 26.4 Neurotransmitters control channel activity 26.5 G proteins may activate or inhibit target proteins 26.6 G proteins function by dissociation of the trimer 26.7 Growth factor receptors are protein kinases 26.8 Receptors are activated by dimerization 26.9 Receptor kinases activate signal transduction pathways 26.10 The Ras/MAPK pathway 26.11 The activation of Ras 26.12 Activating MAP kinase pathways 26.13 What determines specificity in signaling? 26.14 Cyclic AMP and activation of CREB 26.15 The JAK-STAT pathway 26.16 TGFb signals through Smads 26.17 Structural subunits can be messengers

26.1Introduction Amplification refers to the production of additional copies of a chromosomal sequence found as intrachromosomal or extrachromosomal dna Endocytosis is process by which proteins at the surface of the cell are internalized, being transported into the cell within membranous vesicles G proteins are guanine nucleotide-binding proteins. Trimeric G proteins are associated with the plasma membrane. When bound by gdp the trimer remains intact and is inert. When the GDP is replaced by GTP, the a subunit is released from the bg dimer. Either the a monomer or the bg dimer then activates or represses a target protein. Monomeric G proteins are cytosolic and work on the same principle that the form bound to GDP is inactive. but the form bound to gtp is active 请莘大

Amplification refers to the production of additional copies of a chromosomal sequence, found as intrachromosomal or extrachromosomal DNA. Endocytosis is process by which proteins at the surface of the cell are internalized, being transported into the cell within membranous vesicles. G proteins are guanine nucleotide-binding proteins. Trimeric G proteins are associated with the plasma membrane. When bound by GDP the trimer remains intact and is inert. When the GDP is replaced by GTP, the a subunit is released from the bg dimer. Either the a monomer or the bg dimer then activates or represses a target protein. Monomeric G proteins are cytosolic and work on the same principle that the form bound to GDP is inactive, but the form bound to GTP is active. 26.1 Introduction

26.1 Introduction Receptor is a transmembrane protein, located in the plasma membrane, that binds a ligand in a domain on the extracellular side and as a result has a change in activity of the cytoplasmic domain (The same term is sometimes used also for the steroid receptors, which are transcription factors that are activated by binding ligands that are steroids or other small molecules.) Second messengers are small molecules that are generated when a signal transduction pathway is activated The classic second messenger is cyclic AMP, which is generated when adenylate cyclase is activated by a g protein(when the g protein itself was activated by a transmembrane receptor Signal transduction describes the process by which a receptor interacts with a ligand at the surface of the cell and then transmits a signal to trigger a pathway within the cell 消当

Receptor is a transmembrane protein, located in the plasma membrane, that binds a ligand in a domain on the extracellular side, and as a result has a change in activity of the cytoplasmic domain. (The same term is sometimes used also for the steroid receptors, which are transcription factors that are activated by binding ligands that are steroids or other small molecules.) Second messengers are small molecules that are generated when a signal transduction pathway is activated. The classic second messenger is cyclic AMP, which is generated when adenylate cyclase is activated by a G protein (when the G protein itself was activated by a transmembrane receptor). Signal transduction describes the process by which a receptor interacts with a ligand at the surface of the cell and then transmits a signal to trigger a pathway within the cell. 26.1 Introduction

Movement of ligand Signal transduction S EXTRACELLULAR Ligand binds to receptors 26.1 Introduction Figure 26.1 Overview information may be transmitted from the exterior to the interior of the cell by movement of w a ligand or by signal CYTOSOL transduction gand released Rece ptor interacts cytoplasm LpI rotein 消当

Figure 26.1 Overview: information may be transmitted from the exterior to the interior of the cell by movement of a ligand or by signal transduction. 26.1 Introduction

26.1Introduction Figure 26.2 Three means for transferring material of various sizes into the cell are provided by ion channels. receptor mediated ligand lors ente Lig and s through ch anne released transport and receptor internalization Coated vesicle 消当 ndo closed

Figure 26.2 Three means for transferring material of various sizes into the cell are provided by ion channels, receptor￾mediated ligand transport, and receptor internalization. 26.1 Introduction

26.1Introduction Figure 26. 3A signal may wwii be transduced by Target activating the kinase Target activity of the ↓ cytoplasmic domain of a transmembrane receptor or by dissociating a g P. PY protein into subunits that Target act on target proteins on Phosphory lated receptor G protein dissociates the membrane associates with tar get protein activ e subunit(s) act on target 消当

Figure 26.3 A signal may be transduced by activating the kinase activity of the cytoplasmic domain of a transmembrane receptor or by dissociating a G protein into subunits that act on target proteins on the membrane. 26.1 Introduction

Carrier Channel 26.2 Carriers and channels EXTRACELLULAR olute binds Gate is form water soluble paths to carrier through the membrane w暖日k CYTOSOL Figure 26.4 A carrier(porter) transports a solute into the cell by ↓ a conformational change that EX TRACELLULAR brings the solute-binding site from the exterior to the interior while an ion channel is controlled by the opening of a gate(which might in principle be located on either side Solute expo se d/gate opens: ions/23 of the membrane) to cytoso travel through CYTOSOL 消当

Figure 26.4 A carrier (porter) transports a solute into the cell by a conformational change that brings the solute-binding site from the exterior to the interior, while an ion channel is controlled by the opening of a gate (which might in principle be located on either side of the membrane). 26.2 Carriers and channels form water soluble paths through the membrane

Carrier Channel 26.2 Carriers and channels EXTRACELLULAR olute binds Gate is form water soluble paths to carrier through the membrane w暖日k CYTOSOL Figure 26.4 A carrier(porter) transports a solute into the cell by ↓ a conformational change that EX TRACELLULAR brings the solute-binding site from the exterior to the interior while an ion channel is controlled by the opening of a gate(which might in principle be located on either side Solute expo se d/gate opens: ions/23 of the membrane) to cytoso travel through CYTOSOL 消当

Figure 26.4 A carrier (porter) transports a solute into the cell by a conformational change that brings the solute-binding site from the exterior to the interior, while an ion channel is controlled by the opening of a gate (which might in principle be located on either side of the membrane). 26.2 Carriers and channels form water soluble paths through the membrane

26.2 Carriers and channels form water soluble paths through the membrane Charged face of heliⅸ Hydrophobic face of helⅸ Figure 26.5 A channel may be created by amphipathic helices, which present their hydrophobic faces to the lipid bilayer, while juxtaposing their charged faces away from the bilayer. In this example, the channel is lined with positive charges, which would encourage the passage of anions 消当

Figure 26.5 A channel may be created by amphipathic helices, which present their hydrophobic faces to the lipid bilayer, while juxtaposing their charged faces away from the bilayer. In this example, the channel is lined with positive charges, which would encourage the passage of anions. 26.2 Carriers and channels form water soluble paths through the membrane