Download Signal Receptors 4 types

CELL
COMMUNICATION
CHPT. 11
How do cells
“talk to each
other”….
And what do
they “talk”
about???
They
“talk”
about
getting
together
so they
can mix
genes…
Remember
the
Sordaria
mating?
Remember
the
Sordaria
mating?
Remember
the
Sordaria
mating?
haploid
Diploid
How is this
“mating signal”
transformed into
a form that
brings on a
response?
Exchange of
mating factors
a factor
Receptor
a
Yeast cell, a factor
mating type a
Yeast cell,
mating type a
Mating
a
a
New a/a cell
a/a
Signal- Transduction
series
of steps that takes a
Pathway
signal, on a cell’s surface, &
converts it into a
specific cellular response
inside the cell.
Signal- Transduction
Pathway
without entering any cells… the signal:
“mating factors” cause the cells
to grow towards each other…
Are their “calls”
local
..or are they long
•Local Regulator•communication between nearby
cells.
•Paracrine Signaling- cell
secretes signal into extracellular
fluid and signal acts on nearby
target cells.
many cells can receive
and respond.
•Local
Regulator
-
ex.
Paracrine
•Local Regulator-
•communication between nearby
cells.
•Synaptic- nerve
cell secretes signal
into synapse and
signal acts on a
single target cell.
Only one cell
receives and
responds.
•Long Distance Regulator•communication between cells
some distance apart.
•Hormones- cells
secrete signal into
vessels of circulatory
system. Signal travels
to other parts of body.
Earl W. Sutherland
1915 - 1974
Vanderbilt University
Nobel Prize in
medicine 1971 for
his work in the
mechanisms in the
Earl W. Sutherland
1915 - 1974
Vanderbilt University
He discovered that epinephrine
works by stimulating another
chemical messenger to begin the
sugar-releasing process in the cell
Cell Signaling Overview:
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
Cell Signaling Overview:



Target Cell’s detection of signal from
the OUTSIDE of the cell.
Cell Signaling Overview:



Passing on the signal inside the
cell
Cell Signaling Overview:
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

Cellular
changes b/c of
the signal
smaller molecule that
specifically binds to a
larger one
Usually a protein
Change shape
when acted upon
Receptors 4 types:
1)G-Protein Linked Receptor
receptor in plasma membrane
that works with the help of a
G-Protein
Ligand binding site
G-protein
linked receptor
Interacts with G-protein
b/c GDP is attached
G Protein linked
(ligand)
(G Protein)
b/c GTP is attached
inactivated enzyme
Signal Receptors 4 types:
1)G-Protein Linked Receptor• Signal molecule leaves receptor
• GTP --> GDP
• Turns off response
Signal Receptors 4 types:
1)G-Protein Linked ReceptorVision, smell,
embryonic development,
epinephrine
Bacterial toxins interfere with this
process & causes disease
FYI…whooping cough is a sickness as
a result of a blocked G-protein linked
receptor
Dr. Martin
Rodbell
1994 Nobel Prize ~
Physiology &
Medicine
for the discovery of
the G-Protein and how
Signal Receptors 4 types:
2)Tyrosine-Kinase Receptors-
Signals more than one
signal-transduction
pathway at once
enzyme that
catalyzes the transfer
of phosphate groups
to another molecule
Signal Receptors 4 types:
2)Tyrosine-Kinase Receptors-
acts as
an
enzyme
tyrosine
kinase
Signal Receptors 4 types:
2)Tyrosine-Kinase Receptors-
a phosphate
from ATP
attaches
Signal Receptors 4 types:
2)Tyrosine-Kinase Receptorsligand
attaches:
polypeptides
come
together
6
6
phosphates
attach to the
tyrosines
DIMER!
6
6
relay proteins now
attach & are
activated
6
6
MANY
cellular
responses
Signal Receptors (mostly in cell
membrane) 4 types:
2)Tyrosine-Kinase Receptorssome cancers: CARCENOMAS,
cell reproduction,
growth factor
Signal
molecule
(ligand)
3) Ion-Channel
Receptor-
Gate
closed
Ligand-gated
ion channel receptor
Ions
Plasma
membrane
Gate open
• The [ion] change
triggers cellular
response.
Gate closed
Signal Receptors 4 types:
3) Ion-Channel Receptorex. synapses between nerves
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Signal Receptors 4 types:
4) Intracellular Signals Proteins
located in the cytoplasm or
nucleus that receive a signal that
CAN pass through the cell
membrane. (they are small or
nonpolar)
 ex. - steroids
Signal Receptors 4 types:
4) Intracellular Signals
• Activated
protein
turns on
genes in
nucleus.
Signal Receptors 4 types:
4) Intracellular Signals-
“manly response”
Cell Signaling Overview:
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

signal
is
via. relay
molecules
passed
along
inside
the
cell
PH
HOW???
OS
PH
OR
Y
LA
TION
PH
HOW???
OS
Protein
Phosphoryla
tion
PH
OR

Y
The addition of
Phosphate to a
protein, which
activates the protein.
LA
TION
Remember Kinases?
(from Mitosis)…
General name for any
enzyme that activates
or inactivates other
proteins by
transferring a
phosphate to the
relay
WHAT???
molecules
are
typically
protein
KINASES
relay
WHAT???
molecules
interact
with
each other
and pass
information
into the nucleus
connect/activates
t transfer of P. to
inactive
transfer of P.
to inactive
These are second
messengers!!
Intended response
Sometimes, not all
parts of the pathway
are proteins
second
messengers
ATP converts to cAMP =
via. enzyme
cAMP relays a signal from
membrane into cytoplasm
cAMP = “megaphone” molecule /
that simply activates another
protein usually
a kinase.
Susan
Taylor
Univ. of Cal
Discovered
cAMP
cAMP usually
activates protein
kinase A, which
phosphorylates
various other
proteins
signaling pathways regulate the synthesis of
enzymes or other proteins, usually by turning
genes on or off in the nucleus
Summary
• Don’t get bogged down in all
details in this chapter.
Use the KISS principle.
• Know - 3 stages of cell signaling.
• Know - At least one example of a
receptor and how it works (in
detail).
Cell Signaling Overview:



Aging process is initiated at
the cellular level…
QuickTime™ and a
decompressor
are needed to see this picture.
QuickTime™ and a
decompressor
are needed to see this picture.
Aging process is initiated at
the cellular level…
after a certain number of
cell divisions, the cell
looses its ability to
respond to signals:
APOPTOSIS
Aging process is initiated at
the cellular level…
What is the evolutionary
significance of cell death
(APOPTOSIS)?