cytoskeleton; intermediate filaments Flashcards
where are they found
- nearly all mammal cells
- absent from plants and fungi
structure and function
rope like network of filaments
principal function is to maintain cell structure and tensile strength
IF differ from AF and MT
- no defined polarity
- no associated motor proteins
- dont bind to nucleotides; ATP, GTP
- very stable in comparison
4 types of IFs
- cytoplasmic; keratins, vimentin and vimentin related, neurofilaments
- nuclear; nuclear lamins
function of IF in cytoplasm
- tensile strength; withstand mechanical stress
- structural support; creating deformable 3D structure, reinforcing cell shape and fix organelle localisations
stratified squamous epithelium
- stem cells interior
- dead cells at outmost surface
- keratin remains; hard, waterproof, resists abrasions
- makes up hair, nails, skin, feathers
what do keratins do?
form strong network indirectly linked to neighbouring cells
hemidesmosomes
mediate cell-matrix adhesion between epithelial cells and basal lamina
- integrins a6b4 binds to proteins in plaques to lamin in ECM
what does disruption of keratin networks cause
blisters
vimentin required for what
trans-epithelial migration
endothelial migration
WBCs leave blood stream to combat infection
- process impaired in mutant mice
desmin filaments function
maintain muscle structural integrity
mutant mice=misaligned muscle fibres
mutations in humans = muscle disorders
desmin filaments structure
tethered to Z disk like sarcomere
neurofilaments
have side arm projections from core filaments
fill and pack cytoplasm with neurons
charcot-marie-tooth disease
peripheral nervous system degenerates