4.2 Signal Transduction

• Transduction is the second stage of cell communicaion
• There are diff types of signal transduction pathways like protein modification and phosphorylation cascades
• Protein modification regulates protein synthesis by switching on/off genes in the nucleus
• Protein modifications regulate activity of proteins in the cytoplasm
• Cascades are long chains of molecular interactions. They relay signals from receptors to target molecules
• Phosphorylation cascades enhance and amplify signals
• Signaling begins with the recognition of a chemical messenger called a ligand by a receptor protein in the target cell
• There are three classes of membrane receptors: Ligand-gated ion channels, Catalytic (enzyme-linked receptors), and G-protein-linked receptors
• Ligand-gated ion channels are channels in the plasma membrane that open or close when a particular ligand binds to them