Lecture 10: Cell migration

Question 1

What are lamellipodia

Answer 1

thin, sheet-like membrane protrusions found at the leading edge (front) of motile cells (BRANCHED)

Made up of actin filaments in a mesh like structure

Question 2

Name of protein that gives lamellopodia mesh like structure

Answer 2

Arp2/3 complex

Question 3

2 key functions of arp 2/3

Answer 3

nucleates assembly of new actin filaments
And
prevents disassembly at the minus end

Question 4

Where do actin filaments disassemble in lamellipodia

Answer 4

at the rear end
Arp starts to come off so it means they don’t just grow forever

Question 5

What are filopodia

Answer 5

parallel extensions of actin filaments
They extend beyond lamellopodia

Question 6

Name of proteins that allow filopodia to extend

Answer 6

formins
They simply add actin monomers to the plus end to extend it out

Question 7

What keeps the filopodia anchored

Answer 7

Interactions with other actin filaments
Via cross linked proteins

Question 8

Key function of filopodia

Answer 8

guiding migrating cell
Like antennae
Probes the environment to make new contact with environemnt

Question 9

What are the two ways protrusions adhere to the surface

Answer 9

focal contacts with membrane proteins called integrins
And
Contractile actin bundles which attach to the focal contacts

Question 10

How is the rear end of the cell pulled forward

Answer 10

myosin II

Question 11

What type of protein is important to establish cell polarity

Answer 11

microtubule capping proteins
Stabilises growing microtubules

Question 12

How is cell migration important in the immune system

Answer 12

allows movement of cells such as neutrophils to respond to chemoattractants and move towards bacteria, open wound etc.

Question 13

what are the 2 types on intermediate filaments

Answer 13

cytoplasmic
nuclear

Question 14

what are the 3 types of cytoplasmic intermediate filament

Answer 14

keratin filaments
vimentin (e.g. desmin)
neurofilaments

Question 15

what are the intermediate filaments in nucleus

Answer 15

nuclear lamins

Question 16

fucntion of nuclear lamin

Answer 16

sternghtens nucleus
importantn in cells that have to squeeze through small spaces

Question 17

what can mutations in nuclear lamins lead to

Answer 17

progeria

Question 18

what nulcleotides do intermediate filaments bind to

Answer 18

trick question
they dont bind to any
ha

Question 19

IFs are generally stable, but at what point in cell cycle do they disassemble

Answer 19

during cell division
triggered by phosphorylation

Question 20

how are keratin filaments linked between cells

Answer 20

via desmosomes
which is why desmosomes being mutated is bad

Question 21

what can keratin mutations cause

Answer 21

blistering of the skin

Question 22

where is desmin found

Answer 22

remember, desmin is a type of cytoplasmic IF
found in cardiac muscle
skeletal muscle
smooth muscle

Question 23

what can desmin mutations cause

Answer 23

muscular dystrophy
cariac myopathy

Question 24

hwo is desmin in adjacent cells

Answer 24

via desmosomes

Question 25

what are the level of intermediate filament assembly

Answer 25

the monomer is an alpha helix
this turns into a coiled coil dimer
which then stacks to form a tetramer (2 dimers on top of each other)
8 of these tetramers come together to form the filament

Question 26

wha protein links IFs, actin filaments, microtubules together

Answer 26

plectin

Question 27

what can plectin mutations cause

Answer 27

skin disruption
muscular dystrophy
neurdegeneration