Cellular Communication
Chapter 11
Local communication
In what ways do
cells communicate
locally?
•In what ways do
cells communicate
over longer
distances?
Regulation by chemical
messengers
•
Neurotransmitters released by neurons
•
Hormones release by endocrine glands
endocrine gland
neurotransmitter
axon
hormone
carried by blood
receptor proteins
receptor proteins
target cell
Lock & Key
system
Three Stages of Cell Signaling
EXTRACELLULAR
FLUID
1 Reception
Receptor
Signaling
molecule
CYTOPLASM
Plasma membrane
Fig. 11-6-2
EXTRACELLULAR
FLUID
1 Reception
CYTOPLASM
Plasma membrane
2 Transduction
Receptor
Relay molecules in a signal transduction pathway
Signaling
molecule
Fig. 11-6-3
CYTOPLASM
EXTRACELLULAR
FLUID
Plasma membrane
1 Reception
2 Transduction
3 Response
Receptor
Activation
of cellular
response
Relay molecules in a signal transduction pathway
Signaling
molecule
Steroid
Hormones:
Hormone
(testosterone)
EXTRACELLULAR
FLUID
Plasma
membrane
Receptor
protein
DNA
NUCLEUS
CYTOPLASM
What type of
Molecule is
a steroid?
Hormone
(testosterone)
EXTRACELLULAR
FLUID
Plasma
membrane
Receptor
protein
Hormonereceptor
complex
DNA
NUCLEUS
CYTOPLASM
Hormone
(testosterone)
EXTRACELLULAR
FLUID
Plasma
membrane
Receptor
protein
Hormonereceptor
complex
DNA
NUCLEUS
CYTOPLASM
Hormone
(testosterone)
EXTRACELLULAR
FLUID
Plasma
membrane
Receptor
protein
Hormonereceptor
complex
DNA
mRNA
NUCLEUS
CYTOPLASM
Hormone
(testosterone)
EXTRACELLULAR
FLUID
Plasma
membrane
Receptor
protein
Hormonereceptor
complex
DNA
mRNA
NUCLEUS
CYTOPLASM
New protein
Peptide Hormones
Nuerotransmitters
How will the
structure of
these molecules
cause
them to target
a cell
differently?
signal-transduction pathway
Action of protein hormones
1
protein
hormone
P
reception
plasma membrane
binds to receptor protein
activates
G-protein
activates enzyme
cAM
P
receptor
protein
activates
cytoplasmic
signal
GTP
cytoplasm
target cell
acts as 2° messenger
transduction
ATP
ATP
activates
enzyme
2
secondary
messenger
system
activates
enzyme
produces an action
3
response
Ex: Action of epinephrine
(adrenaline)
adrenal gland
signal
1
epinephrine
activates
G protein
receptor
protein
in cell
membrane
activates GTP
3
activates
adenylyl cyclase
cAMP
GDP
transduction
4
GTP
2
ATP
activates
protein kinase-A
5
activates
phosphorylase kinase
cytoplasm
liver cell
released
to blood
activates
glycogen phosphorylase
glycogen
6
glucose
7
response
1
Ion
Channel
Receptors
Signaling
molecule
(ligand)
Gate
closed
Ligand-gated
ion channel receptor
Ions
Plasma
membrane
2 Gate open
Cellular
response
3
Gate closed
Seen with
neurotransmitters
Transduction
Signaling molecule
Receptor
Activated relay
molecule
Inactive
protein kinase
1
Active
protein
kinase
1
Inactive
protein kinase
2
ATP
ADP
Pi
P
Active
protein
kinase
2
PP
Inactive
protein kinase
3
ATP
ADP
Pi
Active
protein
kinase
3
PP
Inactive
protein
P
ATP
P
ADP
Pi
PP
Active
protein
Cellular
response
Second Messengers
Fig. 11-11
First messenger
Adenylyl
cyclase
G protein
G protein-coupled
receptor
GTP
ATP
cAMP
Second
messenger
Protein
kinase A
Cellular responses
Benefits of a 2° messenger system
signal
1
Activated adenylyl cyclase
receptor protein
2
Not yet
activated
amplification
4
3
GTP
amplification
cAMP
amplification
5
G protein
protein kinase
6
Amplification!
amplification
enzyme
Cascade multiplier!
FAST response!
7
amplification
product
Cellular Response
EXTRACELLULAR
FLUID
Signaling molecule
(first messenger)
G protein
DAG
GTP
G protein-coupled
receptor
Phospholipase C
PIP2
IP3
(second messenger)
IP3-gated
calcium channel
Endoplasmic
reticulum (ER)
CYTOSOL
Ca2+
EXTRACELLULAR
FLUID
Signaling molecule
(first messenger)
G protein
DAG
GTP
G protein-coupled
receptor
Phospholipase C
PIP2
IP3
(second messenger)
IP3-gated
calcium channel
Endoplasmic
reticulum (ER)
CYTOSOL
Ca2+
Ca2+
(second
messenger)
EXTRACELLULAR
FLUID
Signaling molecule
(first messenger)
G protein
DAG
GTP
G protein-coupled
receptor
PIP2
Phospholipase C
IP3
(second messenger)
IP3-gated
calcium channel
Endoplasmic
reticulum (ER)
CYTOSOL
Various
proteins
activated
Ca2+
Ca2+
(second
messenger)
Cellular
responses
Fig. 11-14
Growth factor
Reception
Receptor
Phosphorylation
cascade
Transduction
CYTOPLASM
Inactive
transcription
factor
Active
transcription
factor
P
Response
DNA
Gene
NUCLEUS
mRNA
Fig. 11-15
Reception
Binding of epinephrine to G protein-coupled receptor (1 molecule)
Transduction
Inactive G protein
Active G protein (102 molecules)
Inactive adenylyl cyclase
Active adenylyl cyclase (102)
ATP
Cyclic AMP (104)
Inactive protein kinase A
Active protein kinase A (104)
Inactive phosphorylase kinase
Active phosphorylase kinase (105)
Inactive glycogen phosphorylase
Active glycogen phosphorylase (106)
Response
Glycogen
Glucose-1-phosphate
(108 molecules)
Homology in hormones
What does this tell you about these hormones?
How could these hormones have different effects?
same gene family
gene duplication?
prolactin
mammals
milk
production
birds
fat
metabolism
fish
amphibians
salt &
water
balance
metamorphosis
& maturation
growth
hormone
growth
& development
How can 1
signal
molecule
have multiple
responses?
Let’s go to the
Video!
Apoptosis
Cell signaling example
Fig. 11-19
2 µm
Fig. 11-20a
Ced-9
protein (active)
inhibits Ced-4
activity
Mitochondrion
Receptor
for deathsignaling
molecule
Ced-4 Ced-3
Inactive proteins
(a) No death signal
Fig. 11-20b
Ced-9
(inactive)
Cell
forms
blebs
Deathsignaling
molecule
Active Active
Ced-4 Ced-3
Activation
cascade
(b) Death signal
Other
proteases
Nucleases
Fig. 11-21
Interdigital tissue
1 mm