Sensory Transduction Gordon L. Fain University of California, Los Angeles with illustrations by Margery J. Fain Sinauer Associates, Inc. Publishers Sunderland, Massachusetts U.S.A.
Brief Contents Chapter 1 The Senses 1 Chapter 2 Mechanisms of Sensation 19 Chapter 3 Channels and Electrical Signals 43 Chapter 4 Metabotropic Signal Transduction 69 Chapter 5 Mechanoreceptors and Touch 93 Chapter 6 Hair Cells and the Detection of Movement and Sound 119 Chapter 7 Chemoreception and the Sense of Smell 159 Chapter 8 Taste 191 Chapter 9 Photoreception 215 Chapter 10 Extra Sensory Receptors 261
Contents Chapter 1 The Senses 1 Early Studies of the Anatomy of the Sense Organs 2 The Physiology of Sensation 5 Cracking the Problem: Molecular Physiology 9 The Revolution of Molecular Biology 11 The Code Deciphered: Sensory Transduction 16 Summary 17 Chapter 2 Mechanisms of Sensation 19 Sensory Membrane 21 Organization of Membrane and Sensory Protein 24 Membrane Renewal 26 External Specializations 29 Detection of the Stimulus 34 Primary and Secondary Receptor Cells 35 Sensitivity of Transduction 37 Noise 39 Sex Pheromone Detection in the Male Moth 39 Summary 41
viii CONTENTS Chapter 3 Channels and Electrical Signals 43 Structure and Function of Ion Channels 43 The Structure of the Pore 45 Gating 46 Ionotropic Receptor Molecules 48 Membrane Potentials 51 The Nernst Equation 52 Ion Homeostasis 55 The Goldman Voltage Equation 57 Driving Force and Voltage Change 58 The Voltage Response of Hair Cells 59 The Technique of Voltage Clamping 60 Voltage Clamping the Hair Cell 63 Ion Selectivity 66 Summary 68 Chapter 4 Metabotropic Signal Transduction 69 G Protein-Coupled Receptors 72 Heterotrimeric G Proteins 75 Effector Molecules 77 Second Messengers 80 Calcium and NO 82 Channels Gated by Second Messengers 84 A Metabotropic Sensory Receptor 87 Summary 90 Chapter 5 Mechanoreceptors and Touch 93 Mechanoreception in Paramecium 93 Transduction of Touch in the Roundworm Caenorhabditis Elegans 96 Crayfish Stretch Receptor 101
CONTENTS ix Insect Mechanoreceptors 107 Mechanoreceptors and Touch in Mammals 111 Molecular Biology of Mechanoreception in Mammals 115 Summary 117 Chapter 6 Hair Cells and the Detection of Movement and Sound 119 Tip Links 123 The Channels 126 Gating and Bundle Stiffness 129 Adaptation of Hair Cells 134 Modulation of Sensitivity 138 Organs of the Lateral Line 140 The Vestibular System 142 The Cochlea 146 Endolymph and Endocochlear Potential 149 Outer Hair Cells and Tuning 151 Electrical Resonance 154 Summary 156 Chapter 7 Chemoreception and the Sense of Smell 159 Chemotaxis 159 Olfaction in Insects 164 Receptor Proteins and Coding in Insects 167 Olfaction in Vertebrates: The Nasal Epithelium 169 Olfactory Receptor Proteins 171 The Mechanism of Transduction in Vertebrates 172 Desensitization and Adaptation 178 Olfactory Coding 181 The Olfactory Bulb 182 Alternative Mechanisms of Transduction 184 Vomeronasal Organ 185
x CONTENTS Summary 188 Chapter 8 Taste 191 Gustation in Insects 193 Mammals: Taste Buds and the Tongue 197 The Transduction of Taste 199 Bitter 202 Sweet 203 Umami 205 Salty 206 Sour 209 Summary 212 Chapter 9 Photoreception 215 Photopigment Activation 217 Phototransduction 219 The Photoreceptors of Arthropods 222 Transduction in Arthropods 226 Photoreceptor Channels in Arthropods 230 The Role of Ca 2+ in the Regulation of Gain and Turn-Off 234 Vertebrate Rods and Cones 237 Transduction in Vertebrate Photoreceptors 239 Ion Channels of Rods and Cones 242 The Photocurrent 244 Shutting Down the Light Response 248 Light Adaptation 253 Pigment Renewal and the Recovery of Sensitivity after Bright Light 256
CONTENTS xi Summary 258 Chapter 10 Extra Sensory Receptors 261 Thermoreception 262 Seeing in the Dark: Heat Receptors as Detectors of Infrared 267 Electroreception 271 Tuberous Receptors and Electrolocation 277 Magnetoreception 282 Summary 288 References 291 Index 329