Trigger and Amplification Mechanisms in Visual Phototransduction

PERSPECTIVES AND OVERVIEW 332 The Retinal Rod Outer Segment: a Model System for Biophy.�ical Studies 332 From the Photoisomerization of Retinal to the Hyperpolarization of the Rod: a Missing Link Between cGMP HydrolySis and Calcium Release? 332 Molecular Structure, Trigger, and Amplification Mechanisms 334 ORGANIZATION AND STRUCTURE IN THE ROD 335 The Disc Unit : Membrane, Intradiscal, and Cytoplasmic Compartments 335 Rhodopsin Structure: Evidence from Biophysical Approaches 337 The Peripheral and Soluble Proteins: Transducin, PDE, Kinase, "4BK" 341