Intermediate Filaments

Question 1

stucture of intermediate filaments

Answer 1

polymers

Question 2

diameter of intermediate filaments

Answer 2

10nm

Question 3

number of genes encode intermediate filaments

Answer 3

70 genes

Question 4

polarity of intermediate filaments

Answer 4

intermediate filaments not polarized

Question 5

overall structure of intermediate filament dimer: N-terminus to C-terminus

Answer 5

N’ -Head - Rod - Tail - C’

Question 6

domain of IF proteins conserved

Answer 6

rod domain

Question 7

IF N’ and C’ domains makes the dimer:

Answer 7

polarized

Question 8

structure of IF rod domain

Answer 8

alpha-helical, coiled-coil structure

Question 9

alpha-helix in rod domain characterized by:

Answer 9

heptad repeat sequence

Question 10

type of IF residues help back two proteins together

Answer 10

hydrophobic residues

Question 11

IF rod domain has hydrophobic residues at positions:

Answer 11

hydrophobic residues at positions 1 and 4

Question 12

fashion in which IF dimers associate with other dimers

Answer 12

anti-parallel fashion

Question 13

tetramers symetric structure makes them:

Answer 13

not polar

Question 14

basic building blocks of intermediate filaments

Answer 14

IF tetramers

Question 15

forms when tetramers assemble end to end

Answer 15

protofilament

Question 16

this forms when four protofilaments assemble

Answer 16

protofibril

Question 17

four protofibrils assemble into:

Answer 17

10nm IF

Question 18

number of interlocked protofilaments IF contains

Answer 18

16 protofilaments

Question 19

number of protofilaments assemble into a protofibril

Answer 19

four protofilaments

Question 20

number of protofibrils assemble into the 10nm IF

Answer 20

four protofibrils

Question 21

IFs are more stable than:

Answer 21

microfilaments or microtubules

Question 22

IFs are more stable than microfilaments or microtubules but are still:

Answer 22

dynamic

Question 23

experiments proves dynamic nature of IFs: this labeled monomer injected into fibroblasts

Answer 23

keratin monomer injected into fibroblasts

Question 24

IFs assemble and dissemble in order of:

Answer 24

hours

Question 25

Class I intermediate filament protein type

Answer 25

acidic

Question 26

Class I intermediate filament distribution

Answer 26

epithelial cells

Question 27

Class II intermediate filament protein type

Answer 27

basic keratins

Question 28

Class II intermediate filament distribution

Answer 28

epithelial cells

Question 29

Class III intermediate filament protein type:

Answer 29

Desmin, GFP, vimentin

Question 30

Class III intermediate filament distribution

Answer 30

muscle, glial cells, mesenchymal cells

Question 31

Class IV intermediate filament protein type

Answer 31

neurofilaments

Question 32

Class IV intermediate filament distribution

Answer 32

neurons

Question 33

Class V interpediate filament protein type

Answer 33

laminins

Question 34

Class V intermediate filament distribution

Answer 34

nucleus

Question 35

IF disease: skin gets blistered

Answer 35

epidermolysis bullosa simplex

Question 36

keratin 14 forms deterodimers with:

Answer 36

keratin 4

Question 37

keratin 14 forms heterodimer with keratin 4 in:

Answer 37

basal cells of epidermis

Question 38

keratin 14 and keratin 4 assemble into:

Answer 38

protofilaments

Question 39

in mature cell keratin 4 and 14 replaced by:

Answer 39

keratin 1 and 10

Question 40

epidermolysis bullosa simplex: keratin 14 and keratin 4 heterodimers cannot form tetramers or protofilaments when:

Answer 40

keratin 14 lacks N- or C- terminal domain

Question 41

epidermolysis bullosa simplex: this lacks N- or C- terminal domain

Answer 41

keratin 14

Question 42

epidermolysis bullosa simplex: these are fragile and unable to withstand abrasion

Answer 42

basal cells of epidermis

Question 43

epidermolysis bullosa simplex: absence of K14/K4 protofilaments seperates:

Answer 43

epidermis from dermis

Question 44

epidermolysis bullosa simplex: caused by epidermis seperating from dermis

Answer 44

blisters

Question 45

IF disease caused by mutations in LMNA:

Answer 45

Hutchinson-Guilford progeria

Question 46

Hutchinson-Guilford progeria caused by:

Answer 46

spontaneuous dominant mutations in Lamin A gene (LMNA)

Question 47

Hutchinson-Guilford progeria: mutations in single base activates:

Answer 47

cryptic splice site

Question 48

Hutchinson-Guilford progeria: mutation produces:

Answer 48

truncated Lamin A protein

Question 49

truncated Lamin A protein called:

Answer 49

progerin

Question 50

premature aging disorder

Answer 50

Hutchinson-Guilford progeria

Question 51

S/S of Hutchinson-Guilford progeria:

Answer 51

baldness, pinched noses, aged skin, dwarfism, craniofacial defects

Question 52

Hutchinson-Guilford progeria: cell part has abnormal morphology

Answer 52

nuclear membrane

Question 53

Hutchinson-Guilford progeria: tissues with high levels of stress (like heart) undergo death due to:

Answer 53

nuclear instability

Question 54

Lamin A synthesized as:

Answer 54

large precursor protein

Question 55

Lamin A large precursor protein modified by addition of:

Answer 55

farnesyl group (lipid)

Question 56

farnesyl modification common in proteins localized to:

Answer 56

membranes

Question 57

cleaves Lamin A precursor at site of farnesyltation before release

Answer 57

Rce

Question 58

Hutchinson-Guilford progeria: farnesyl modification last step being blocked leads to accumulation of intermediate in:

Answer 58

nuclei (which is cytotoxic

Question 59

Hutchinson-Guilford progeria: farnesyl modification intermediate deforms:

Answer 59

nuclei

Question 60

Hutchinson-Guilford progeria: type of drugs used to treat disease

Answer 60

farnesyl transferase inhibitors (FTIs)