Baumann und Seyfried

Question 1

response strength depends on

Answer 1

concentration of the signal
curve can be: all-or-nothing
sigmoidal
hyperbolic

Question 2

Surface receptor act via signaling cascade. At teh target protein that can lead to

Answer 2

altered…
gene expression
shape and movement
metabolisim

Question 3

small (monomeric) G proteins mediate…

Answer 3

 gene expression
 cytoskeleton
 membrane traffic
 nuclear transport

Question 4

temporal response patterns

Answer 4

phasic
tonic
phasic-tonic

Question 5

Adaption/Desensitisation

Answer 5

= change over time in the responsiveness
to a constant stimulus
--> net dynamic range of dose-response
function higher

Question 6

PKA (protein kinase A)

Answer 6

cyclic AMP dependent protein kinase (PKA or A-kinase)
• tetramer of 2 catalytic and 2 regulatory subunits
• each regulatory subunit with 2 cAMP-binding sites
• binding of 4 cAMP –> catalytic subunits dissociate & are active
• catalytic subunit = Ser/Thr kinase

Question 7

Calcium ion influx - how are the channels opened?

Answer 7

voltage opened
store opened
seccond messenger opened
receptor opened

Question 8

Cell Polarity

Answer 8

“persistent asymmetrical and ordered distribution of structures (or molecules) along an axis”

Question 9

The basic tissue types in animals

Answer 9

• epithelia
• nervous tissue
• muscular tissue
• connective tissue

Question 10

Epithelia

Answer 10

• line outer & inner sufaces of the body
• have two sides exposed to different environments
• are linked by junctional complexes

Question 11

Molecular components of tight junctions

Answer 11

Claudin(s): homophilic interaction
Occludin: homophilic interaction
JAM = junctional adhesion molecule:
member of Ig superfamily
homophilic interaction

all contain
ZO-1, -2, -3: (zonula occludens) scaffolding proteins

Question 12

zonula occludens contain which domains?

Answer 12

PDZ: binds other PDZ domains and Cterminal motifs –> protein complex
SH3: binds proline-rich motifs
GUK: protein binding
ABR: F actin binding

Question 13

What are Cadherins?

Answer 13

• „calcium-dependent adhesion“
• cell adhesion molecules
• > 100 different cadherins by multiple genes & alternative RNA splicing

structure:
extracellular cadherin domains: Ca2+ binding –> forming homodimer
transmembrane domain
cytoplasmic tail: interaction with adopter and signaling proteins

Question 14

Gap junctions

Answer 14

6x connexin = connexon
= hemichannel

pore Ø ̴1.4 nm
- passage of molecules up to 1000 Da (anorganic ions, incl. Ca2+; water; sugars; AA; metabolites; nucleotides incl. ATP & cAMP; IP3)
 no passage of proteins
 can be closed (regulated by e.g. Ca2+)

Question 15

things enriched basolateral

Answer 15

Phosphatidylcholine

lipids: PIP2, PTEN

Question 16

things enriched apical

Answer 16

Sphingomyelin
Glycolipids
Cholesterol
(lipids: PIP3, PI3 kinase)

Question 17

Cell polarity is expressed at all hierarchical levels

Answer 17

• cell morphology
• organisation of the plasma membrane into domains that differ by molecular composition and function
• heterogeneous distribution of organelles in the cytoplasm
• polar organisation of the cytoskeleton (MTs, F-actin)
• heterogeneous distribution of proteins / mRNA in the cytoplasm

almost every cell in animals is polar

Question 18

Basolateral sorting signals

Answer 18

–> identification and binding by clathrin-adaptor protein complex AP-1
4 SU (2 small and 2 big ones)
binding of AP-1 by clathrin –> vesicle formation

Question 19

diffusional barriers

Answer 19

Ankrin
Spektrin
Na/K-ATPase
cell adhesion molecule

• endocytosis reduced
• proteins retained in the membrane

Question 20

tight junctions hinder and prevent - what?

Answer 20

• tight junctions hinder exchange of membrane proteins between apical & basolateral domain
• tight junctions prevent diffusion of membrane lipids in the outer leaflet of the plasma membrane between apical & basolateral domain