Signal Transduction

Cellular Metabolism - CH12

• The Cell

How cells talk to each other

Micro-cellular Pathways

Signal Transduction/Cell Signaling

Function/Purpose:

• Sending and receiving information from cells to cells
  • Why have secondary messengers?
  • Why have additional signaling proteins?
  • Why not just use the membrane receptors?
    • Delegation, versatility, efficiency

Fundamentals:

Basics

• Signal
  • Release of primary messenger
• Reception
  • Weak Interactions
• Amplification & Transduction
  • Secondary messenger effects
• Response
• ST Termination
  • Receptor-ligand interactions are reversible

SigTrans Analogy: Human Interaction

Phases of Signal Transduction:

• Intercellular Signal Transduction InterSigTrans - Release
• Intracellular Signal Transduction IntraSigTrans - Alteration

Anatomy/Components of Signal Transduction:

Types of Primary Messengers

• Hormones
• Energy Charge/State - ATP, NADH, GTP, FADH2

Types of Receptors:

• Intracellular Receptors
• Cell Surface Receptors

Types of Secondary Messengers

• Nucleotides
  • cAMP
  • cGMP
• Ions
  • Calcium (CA)
• Lipids
  • IP3
  • DAG

Examples of Modalities/Cascades/Paths

• beta-Adrenergic Receptor/G Protein/Adenylate Cyclase (AC)/Protein Kinase A (PKA)/Phosphorylase Kinase//Glucagon Interactions
• CCK Receptor]/G Protein/Phospholipase C (PLC)/Protein Kinase C & IP3 Gated Ion(Ligand-Gated Ion Channels)//Pancreas Zymogen Release-->AcCoA and Insertion Points of Glycolysis
• Janus Kinase 2 (JAK2)/STAT5
• Receptor Tyrosine Kinases (RTKs)/Grb-2/Sos/Ras
• Insulin Receptor/Insulin Receptor Substrates/Phosphoinositide 3-kinase/PIP3-dependent Protein Kinase/Akt Protein Kinase//Increased GLC Transporters on Cell Surface

Concepts:

• Enzymes
• Organelles
• Km and affinity
• Polarity
• Biomolecules

Terminology:

• Transduction: conversion of signal into other chemical forms
• Primary Messenger: chemical that binds to a receptor with a particular result
  • Agonist: chemical that binds to a receptor to trigger a response (signal transduction)
  • Antagonist: chemical that binds to a receptor to deactivae a response (signal transduction)
• Effector Proteins: signaling proteins that act by agonist binding
• Secondary Messengers: small intracellular molecuels that transmit or amplify the signal (come from effectors)
• Juxtacrine: Juxtracrine
• Endocrine: Endocrine
• Intracellular Signal Transduction IntraSigTrans
• Intercellular Signal Transduction InterSigTrans
• Intracellular Receptors: regulate gene activity Intracellular Receptor
• Cell Surface Receptors Cell Surface Receptor
• Ligand

Additional Information:

• Wikipedia