M1-C2-L7 --> Cytoskeleton

Front 1

Function of cytoskeleton X 2

Back 1

1.) Cell shape and structure
2.) Mechanochemical movement

Front 2

The three basic filaments of cytoskeleton

Back 2

1.) Actin
2.) Microtubules
3.) Intermediate filament

Front 3

How are filament systems held together?

Back 3

By weak non-covalent bonds

Front 4

Describe the types of IF's involved in cell to cell adhesion.

Back 4

1.) Desmosomes (connection between cells)
2.) Hemidesmosomes (connection between cells and matrix)
3.) Keratin (connection between cells and organelles)

Front 5

Describe the types of IF's involved in muscles.

Back 5

DESMINS provide a scaffold cage for skeletal muscles.

Front 6

Common IF structural similarities.

Back 6

1.) Globular amino-terminal domain. (HEAD)
2.) Central alpha helical domain. (BODY)
3.) Globular C-terminus domain. (TAIL)

Front 7

How does IF's initially begin folding?

Back 7

As coiled coil dimers.

Front 8

Different types of IF coiled coil dimers.

Back 8

1.) Homopolymeric
2.) Heteropolymeric

Front 9

Where are the modifications (dissociations) and regulations occuring on IF's?

Back 9

On the C-terminus ends

Front 10

Why are hair keratins so stable and insoluble?

Back 10

Due to high cysteine residues on the end forming disulfide crosslinks.

Front 11

IF's are composed of what subunits?

Back 11

IF's consist of 4 PROTOFIBRILS

Front 12

What are protofibrils composed of?

Back 12

Protofibrils composed of 2 APOLAR PROTOFILAMENTS

Front 13

What are the apolar protofilaments composed of?

Back 13

Apolar Protofilaments composed of 2 polar coiled coil dimers in antiparallel tetramer form

Front 14

Individual coiled coiled domains have what type of repeat?

Back 14

heptad

Front 15

Why do IF's not have the dynamic nature of actins or microtubules?

Back 15

Due to lack of polarity.

Front 16

What are the benefits of IF's in regards to actin or myosin?

Back 16

Greater combo of strength, stability, and flexibility.

Front 17

For the most part, how are IF's regulated?

Back 17

By phosphorylation (sometimes by proteolysis)
in globular region.

Front 18

What enzyme breaksdown IF's in nucles?

Back 18

Cyclin-dependent Kinase (CDK)

Front 19

What enzyme is responsible for IF assembly?

Back 19

Protein Phosphatase I (PP1)

Front 20

Functions of IF's X 2.

Back 20

1.) Mechanical(protection and structure)
2.) Non-mechanical (stress sensor and signaling)

Front 21

Two diseases associated with gene mutations affecting the mechanical mechanism of IF.

Back 21

1.) EBS (Epidermolysis Bulbosis Simplex)
2.) EH (Epidermolysis Hyperkeratosis)

Front 22

Disease associated with defect in LMNA gene.

Back 22

Hutchingson-Gilford Progeria

Front 23

What are the globular, nucleotide-binding protein subunits in actin?

Back 23

Actin monomers

Front 24

What are the globular, nucleotide-binding protein subunits in microtubules?

Back 24

Alpha and beta tubulin heterodimers.

Front 25

Describe the ends of actin.

Back 25

Barbed polar (+) end

Pointed polar (-) end

Front 26

Describe the ends of microtubules.

Back 26

Just (+) and (-) ends

Front 27

Nucleotide binding for actin?

Back 27

ADP/ATP

Front 28

Nucleotide binding for microtubules?

Back 28

GDP/GTP

Front 29

Where do you find actins X 6?

Back 29

1.) Muscle
2.) Microvilli of intestintal brush border
3.) Movement/Growth of Cell
4.) Cleavage Furrow of cytokinesis
5.) Vesicle movement
6.) Stero cilia in ear.

Front 30

What are the two forms that actin can exist as?

Back 30

1.) Parallel bundles
2.) 2D or 3D networks

Front 31

Two important concepts of actin.

Back 31

1.) Dynamic polymerization/depolymerization.
2.) Association with molecular motors.

Front 32

Why is nucleation of a helical polymer difficult?

Back 32

Because you need multiple and simultaneous contacts. You need at least three to spontaneously join to get the required fourth.

Front 33

What causes the rate limiting for polymerization in actin?

Back 33

Concentration of polymers

Front 34

What are the principles that govern actin dynamics?

Back 34

1.) Regulation of Bound nucleotide.
2.) Regulation of Elongation
3.) Regulation of Nucleation
4.) Regulation of Severing filaments.

Front 35

Describe Regulation of Bound Nucleotide.

Back 35

Factors that facilitate ADP/ATP exchange on actin....
and GDP/GTP exchange on microtubules.

Front 36

Describe Elongation regulation.

Back 36

Factors that alter rate of elongation?

Front 37

Give an example of protein that regulates bound nucleotides?

Back 37

PROFILIN facilitates ADP/ATP exchange in actin.

Front 38

Give an example of Elongation regulation protein?

Back 38

End-specific capping proteins.

Front 39

Describe regulation of nucleation?

Back 39

Proteins that regulate nucleation.

Front 40

Provide example of nucleation regulation protein.

Back 40

Arp complex

Front 41

Describe regulation of severing filaments.

Back 41

Proteins that sever filament in middle

Front 42

Provide example of regulation protein that severs filaments.

Back 42

Gelsolin

Front 43

Give an example of non-mechanical function of IF's.

Back 43

Wound signalling for healing

Front 44

In regards to LMNA, what is the reason for disease phenotypes such as Progeria?

Back 44

Accumulation of farnesylated Lamin A.

Front 45

What is the most abundant type of protein in cell?

Back 45

Actin