Cellular Communication Chapter 11

Local communication In what ways do cells communicate locally? In what ways do cells communicate over longer distances?In what ways do cells communicate over longer distances?

Regulation by chemical messengers axon endocrine gland receptor proteins target cell Neurotransmitters released by neurons Hormones release by endocrine glands receptor proteins hormone carried by blood neurotransmitter Lock & Key system

Three Stages of Cell Signaling Reception 1 EXTRACELLULARFLUID Receptor Signalingmolecule Plasma membrane CYTOPLASM 1

Fig Reception 1 EXTRACELLULARFLUID Receptor Signalingmolecule Plasma membrane CYTOPLASM 1 Relay molecules in a signal transduction pathway Transduction 2

Fig EXTRACELLULARFLUID Plasma membrane CYTOPLASM Receptor Signalingmolecule Relay molecules in a signal transduction pathway Activation of cellular response Reception TransductionResponse 1 2 3

Steroid Hormones: Hormone(testosterone) Receptorprotein Plasmamembrane EXTRACELLULARFLUID DNA NUCLEUS CYTOPLASM What type of Molecule is a steroid?

Receptorprotein Hormone(testosterone) EXTRACELLULARFLUID Plasmamembrane Hormone-receptorcomplex DNA NUCLEUS CYTOPLASM

Hormone(testosterone)EXTRACELLULARFLUID Receptorprotein Plasmamembrane Hormone-receptorcomplex DNA NUCLEUS CYTOPLASM

Hormone(testosterone) EXTRACELLULARFLUID Plasmamembrane Receptorprotein Hormone-receptorcomplex DNA mRNA NUCLEUS CYTOPLASM

Hormone(testosterone) EXTRACELLULARFLUID Receptorprotein Plasmamembrane Hormone-receptorcomplex DNA mRNA NUCLEUS New protein CYTOPLASM

Peptide Hormones Nuerotransmitters How will the structure of these molecules cause cause them to target a cell differently?

Action of protein hormones activates enzyme activates enzyme activates enzyme ATP produces an action P cytoplasm receptor protein response reception secondary messenger system signal-transduction pathway acts as 2° messenger target cell plasma membrane binds to receptor protein protein hormone ATP activates cytoplasmic signal cAM P GTP activates G-protein transduction

adrenal gland Ex: Action of epinephrine (adrenaline) activates protein kinase-A activates glycogen phosphorylase activates adenylyl cyclase epinephrine liver cell released to blood receptor protein in cell membrane cytoplasm 6 glycogen activates phosphorylase kinase GTP cAMP 4 activates G protein ATP glucose activates GTP 3 signal transduction response 7 GDP

Ion Channel Receptors Signalingmolecule(ligand) Gateclosed Ions Ligand-gated ion channel receptor Plasmamembrane Gate open Cellularresponse Gate closed Seen with neurotransmitters neurotransmitters

Transduction

Signaling molecule Receptor Activated relay molecule Inactive protein kinase 1 Activeproteinkinase1 Inactive 2 ATP ADP Activeproteinkinase2 P P PP Inactive 3 ATP ADP Activeproteinkinase3 P P PP i ATP ADP P Activeprotein PP P i Inactiveprotein Cellularresponse Phosphorylation cascade i

Second Messengers

First messenger Fig G protein Adenylylcyclase GTP ATP cAMP Secondmessenger Protein kinase A G protein-coupled receptor Cellular responses

Benefits of a 2° messenger system Amplification! signal receptor protein Activated adenylyl cyclase amplification GTPG protein product enzyme protein kinase cAMP Not yet activated FAST response! amplification Cascade multiplier!

Cellular Response

EXTRA-CELLULARFLUID Signaling molecule (first messenger) G protein GTP G protein-coupled receptor Phospholipase C PIP 2 IP 3 DAG (second messenger) IP 3 -gated calcium channel Endoplasmic reticulum (ER) Ca 2+ CYTOSOL

G protein EXTRA-CELLULARFLUID Signaling molecule (first messenger) G protein-coupled receptor Phospholipase C PIP 2 DAG IP 3 (second messenger) IP 3 -gated calcium channel Endoplasmic reticulum (ER) Ca 2+ CYTOSOL (second messenger) GTP

Fig G protein EXTRA-CELLULARFLUID Signaling molecule (first messenger) G protein-coupled receptor Phospholipase C PIP 2 DAG IP 3 (second messenger) IP 3 -gated calcium channel Endoplasmic reticulum (ER) Ca 2+ CYTOSOL Variousproteinsactivated Cellularresponses (secondmessenger) GTP

Fig Growth factor Receptor Phosphorylationcascade Reception Transduction Activetranscriptionfactor Response P Inactivetranscriptionfactor CYTOPLASM DNA NUCLEUS mRNA Gene

Fig Reception Transduction Response Binding of epinephrine to G protein-coupled receptor (1 molecule) Inactive G protein Active G protein (10 2 molecules) Inactive adenylyl cyclase Active adenylyl cyclase (10 2 ) ATP Cyclic AMP (10 4 ) Inactive protein kinase A Active protein kinase A (10 4 ) Inactive phosphorylase kinase Active phosphorylase kinase (10 5 ) Inactive glycogen phosphorylase Active glycogen phosphorylase (10 6 ) Glycogen Glucose-1-phosphate (10 8 molecules)

Homology in hormones prolactin mammals milk production birds fat metabolism amphibians metamorphosis & maturation fish salt & water balance growth & development What does this tell you about these hormones? growth hormone same gene family gene duplication? How could these hormones have different effects?

How can 1 signal molecule have multiple responses?

Let’s go to the Let’s go to the Video!

Apoptosis Cell signaling example

Fig µm

Fig a Ced-9 protein (active) inhibits Ced-4 activity Mitochondrion Ced-4Ced-3 Receptor for death- signalingmolecule Inactive proteins (a) No death signal

Fig b (b) Death signal Death-signalingmolecule Ced-9(inactive) Cellformsblebs ActiveCed-4ActiveCed-3 Activationcascade Otherproteases Nucleases

Fig Interdigital tissue 1 mm