Summary of Cell Biology and Immunology | Biology year 1 | RUG | 2025/26

Cell Biology& Immunology

, I cell
signaling

·

β
Cell-to-cell
signaling
Input/ Signal -
receiver -

Signal processing
-
output / response .




Cell cell-to-cell communication interactions with extracellular and intracellular environment .
signaling encompasses :
,




⑧
Cell-to-cell communication :


1)
Contact-dependent : short , direct

↳
Important in
embryonic development and immune
responses.
2) Paracrine Short modulates
1- O
with
signal molecules responses ↳
:
,
,
.
3)
Synaptic long
:
,
fast ,
with neurotransmitters .
ー
ー
4) Endocrine : slow
long , ,
with hormones, secretion into the blood ,
binding to receptors .




A




Cell
signals can be chemicals or
physical properties
- >
pH ,
temperature , light .


O survive


.D
Integration
D
of multiple allows decision
signals making
⑳
.




in

ω
Extracellular
signals ⑥ Die,
Sa
Cell-surfase intracellular
signal molecules are
hydrophilic ,
signal molecules are
hydrophobic .




↳ ↳ .
large Small > carrier
protein required
-




Different receptor types :

3) o
>
-
lon channel

1) lon shannels )1요
Ligand-gated / voltage gated ASh GABA etc .
-
, , ,




·แนะ
↳
Several multipass transmembrane protein subunits .




2) G-protein-coupled
Ligands: (derivativeshormones
neurotransmitters different erc.
receptors >
protein
-


,




↳


-> G-
7 transmembrane helices ,
single polypepticle chain .



ㆀ protection
17 1 red receplo
↳
Regulate G-protein activity #
3) (RTK)
Enzyme-coupled receptors Receptor tyrosine Kinases
cytokine receptors ~ม
>
-

or .




↳
Signal protein ligands Binding
s induces dimerizationa leads to intracellular
phosphorylation
of the

↳ receptorr.




r
Single pass membrane domain

↳ 000
Directly encode or associated with intracellular kinase . ·
IIll
ขออ แล โป
#

↳
ส่ Enzyme-coupled receptor (RTK)

,Intracellular
signaling
Fast protein function Slow :
protein
signals : altered . altered
synthesis ,
A A A A

↓ k ↓
B B - B B
F ⇐
↓ positive feedback I * negative feedback Cy Incoherent
↓
Leedforward loop G k Coherent feedforward
loop
*
C C C C



Binding-mediated regulation. ligand binding binding
}
and proteins .



Occur in intracellular cascades.

(signaling molecule classes)
Enzymatic regulation GTP-hydrolysis post :
,
translational modifications



Second small molecules CaP CAMP CGMP, IPB hydrophilic
messengers signaling
: :
,
,




diacylglyserol and
phosphatidylinositol
-
hydrophobic .


↳ cat activates calmodulin , important in muscle contraction .




↳ CAMP
CAMP ATP derivative-
is an activates protein kinase A .
is made
by adengl cyclase .




↳ from the PKC and CaPt
Lipid Second
messengers
are released membrane
,
activate release .




GTP-binding proteins are active in GTP-bound State .




↳
區
們晶
GAP



:
GTP-ase of




(
_
Activates - inactivation
protein .




↳ GEF
by Exchanging.
activates >
-

Activation


GPCRs the GTPase.

&バ
have X B and
& subunits - > & is
·
.
、



↑ Trimeric .
'


O= D 0
G-protein(
-




{
p ㅇ &
.
Phosphorylation regulates protein lunction :
QH -
I G-proteins often activate
adenyl cyslase .




Covalent attachment of have different fates for because of the different of attash-
ubiquitin can the sell ,
ways
∅
ment .




8 อ ㆁ "
·




Cell crowded environment
signaling happens
in a .




high affinity
→
with
Receptors bind Signaling
molesuses .




→


Signal proteins and
targets are recruited to a common scaffold.

>
-



Cells mediate multistep processes .

, I The
cytoskeleton
Properties of the
cytoskeleton
The Common characteristiss of
cytoskeleton gives
a cell : in all
types cytoskeleton :




1) 1)
Shape Assembly into macromolecular structures .




2) 2)
Strengths Highly dinamic
3) 3) form
Mobility They large networks


4) Cell 4)
organisation / Transport Assembly and
disassembly regulated by accessory proteins .




tyuexminoero
enm
Thecah atttthe Afnouteets ter spt ' te - lhrell, ot 6


3 of
types cytoskeletal proteins : actin , microtubules ,
intermediate filaments .




intermediate Cilaments



Actin and muscles
Actin two stranded function Shape locomotion
contractility Cytokinesis
: helix ,
5-9 nm ,
:
,
.
, ,




↳ forms
Different macrostructures activ :


←→
>
-
contractile bundle : Stress Liber




rara
- ->




=ardeow
嵩意 whranded
solkmer
nelwea-' ll crter


=
branched network lamellipodium :




parallel bundle. filopodium
light

Actin binds and defines
hydrolyses polarity and directionality
ATP . Monomers are
asymmetric .




↳ ATP-bound bind to the t of the astin filament ATP to ADD
end then
hydrolysed
monomers is .




↳ ADP-bound dissociate -
Because t end it forms stable
easily the keeps
growing
monomers .
,
a cap
.




⑧ TADp ATP
⑧
⑧
^
"ไ θ
·000
?
..
σ 0000 -
_ao
800000
“
_



⑬

十