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Cell communication
Chapter 9
Genes and Development
Fig. 9.1
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External environment
Cytoplasm
Signal
transduction
pathway
Cellular
response
Membrane receptor
Signal
transduction
pathway
Hydrophilic
ligand
Intracellular receptor
Hydrophobic
ligand
Plasma membrane
Cellular
response
Fig. 9.2a
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Direct Contact
Adjacent
plasma
membrane
Plasma
membrane
a.
Fig. 9.2b
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Paracrine Signaling
Secretory cell
Adjacent
target cells
b.
Fig. 9.2c
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Endocrine Signaling
Hormone secretion into
blood by endocrine gland
Blood vessel
Distant target cells
c.
Fig. 9.2d
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Synaptic Signaling
Nerve cell
Neurotransmitter
Synaptic gap
Target cell
d.
Fig. 9.2
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Direct Contact
Paracrine Signaling
Secretory cell
Endocrine Signaling
Hormone secretion into
blood by endocrine gland
Synaptic Signaling
Nerve cell
Neurotransmitter
Adjacent
plasma
membrane
Blood vessel
Plasma
membrane
Adjacent
target cells
Synaptic gap
Distant target cells
Target cell
a.
b.
c.
d.
Fig. 9.3
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Ser
or
Thr
ATP
ADP
Kinase
OH
Ser
or
Thr
O
O
P
O–
O–
Phosphatase
Pi
ATP
Tyr
Kinase
OH
Phosphatase
Pi
O
ADP
Tyr
O
P
O–
O–
Fig. 9.4a
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Ions
Ligand
(signal)
Ions
a.
Fig. 9.4b
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Ligand (signal)
Inactive
Active
Cellular
response
b.
Fig. 9.4c
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Ligand
(signal)
Ions
GPCR
b
G protein
g
a
b
Ion channel
GDP
c.
g
a
Enzyme
G protein activates
GTP
either enzyme or ion channel
a
GTP
Fig. 9.4
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Ligand (signal)
Ions
Ligand
(signal)
Inactive
Active
Cellular
response
Ions
a.
b.
Ligand
(signal)
Ions
GPCR
b
G protein
g
a
b
Ion channel
GDP
c.
g
a
Enzyme
G protein activates
GTP
either enzyme or ion channel
a
GTP
Fig. 9.5
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2. Hormone binding
alters receptor
conformation so it no
longer binds inhibitor.
Hormone
Signal moleculebinding domain
1. Hormones cross
plasma membrane
and bind to
cytoplasmic
receptors.
Inhibitor
5. Cellular
response is
a change in
gene
expression.
DNA-binding
site exposed
Inhibitor
Transcription-activating domain
DNA-binding
site blocked
3. Hormone–receptor
complex translocates
to nucleus.
4. Hormone–receptor
complex binds to DNA.
This usually turns on
transcription, but can
also turn it off.
Gene
transcription
Fig. 9.6
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Ligands
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
P
Phosphate
groups
Dimerization and
autophosphorylation
Transmembrane RTK proteins
P
Cellular
response
P
Phosphorylated protein
Intracellular kinase domain
Extracellular ligand-binding domain
1. Ligand binds to the receptor.
2. Two receptors associate (dimerize)
and phosphorylate each other
(autophosphorylation).
3. Response proteins bind to phosphotyrosine on receptor. Receptor can
phosphorylate other response proteins.
Fig. 9.7
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Insulin
Insulin receptor
a
a
Disulfide bridge
b
1. Insulin binds to the
extracellular domain of
the a-subunit of the
insulin receptor.
b
P
P
P
P
2. The b-subunit of one
insulin receptor
phosphorylates the other,
allowing the insulin response
proteins to be activated.
Insulin
response
protein
P
3. Phosphorylated insulin
response proteins activate
glycogen synthase.
Glycogen synthase
4. Glycogen synthase
converts glucose
into glycogen.
Glycogen
Glycogen
synthase
Glucose
Fig. 9.8a
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MAP kinase cascade
Signal
Receptor
Activator
Ras
First
kinase
MKKK
MKKK
MKKK
MKKK
Active
Inactive
P
Second
kinase
MKK
MKK
MKK
MKK
P
P
Active
Inactive
P
MAP
kinase
MK
Inactive
P
MK
MK
Active
Response
proteins
Response
proteins
Response
Cellular
response
a.
P
Fig. 9.10
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4. MEK activates
MA P kinases (ERK)
2. Ras activates
the first
kinase (Raf)
P
P
3. Raf activates
the second
kinase (MEK)
P
P
P
Response
Response
protein
protein P
P
Raf
P
Ras
P
P
ERK
GT
Response
Response P
protein
protein
Ras
GDP
Response
Response P
protein
protein
MEK
Raf
1. Proteins bound to
receptor activate
Ras by exchanging
GDP for GTP.
ERK
MEK
P
P
P
P
5. MAP kinase (ERK) activates
proteins to produce cellular
responses, including transcription
factors that alter gene expression
Cellular
response
Nuclear
membrane
Activates
Activates
transcription
transcription
factors
factors
Fig. 9.11
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Ligand
GPCR
GPCR
b g
a
Inactive G
protein
GDP
b
g
a
Effector protein
b
gg
a
GTP
GTP
GDP
GTP
Active G
protein
Cellular
response
Pi
Fig. 9.12
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
ATP
cAMP + PPi
NH2
NH2
cAMP
O
–O
P
–O
O
O
P
–O
O
O
P
O
CH2
O
N
CH2
Adenylyl cyclase
–O
N
O
O
O
O
P
–O
O
P
–O
PP i
O
O
O–
P
O–
O–
a.
Extracellular space
Plasma
membrane
O
C
C
O
O
C
C
O
O–
C
O
–O
O
P
O
O
P
Cytoplasm
C
C
O
O
C
C
O–
Cleaved by
phospholipase C
O
OH
OH OH
O–
Phospholipase C
O–
O–
O
O
P O–
P
O
O
O
O
P
DAG
C
OH
O
O
O
O–
IP3
OH
OH OH
O
O
P
O–
PIP2
b.
DAG + IP3
O–
Fig. 9.13
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Ligand
Adenylyl cyclase
GPCR
b
g
b
g
a
GDP
GTP
cAMP
ATP
Cytoplasm
Activates PKA
Response
protein
Nucleus
Cellular
response
Fig. 9.15
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Ligand
Phospholipase C
GPCR
b g
a
GDP
b g
PIP
DAG
GTP
IP3
Cytoplasm
Ca2+
binding
protein
ER
Ca2+
Cellular
response
Fig. 9.16
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Ca2+
Ca2+
Ca2+
Inactive
protein
Calmodulin
Calmodulin
Ca2+
Active
protein
Ca2+
a.
b.
Fig. 9.17
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Epinephrine
Adenylyl
GPCR
cyclase
Adenylyl
cyclase
Glucagon
GTP
GTP
ATP
ATP
cAM P
PKA
Cytoplasm
P
P
P
P
Phosphorylase
kinase
P
P
P
P
Glycogen
phosphorylase
P
CH2
Glycogen
Glucose-6-phosphate