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C2-07 Intermediate Filaments
Boring Cell Stuff
11
Biology
Professional
09/22/2010

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Cards

Term

 

 

 

Cytoskeleton Composed of ........

Definition

1) Intermediate Filaments

 

2) Actin Filaments

 

3) Microtubules

Term

 

 

 

Cytoskeleton's Function

Definition

Framework to maintain cell shape and structure

Mechanism to exert mechanochemical movement

Term

 

 

 

Intermediate Filaments

Definition

Rope-like fibers with 10nm diameter (intermediate between microtubules and actin). 
Provide overall mechanical strength.
Highly evolved and diverse - ~70 functional genes associated with ~30 diseases
Nuclear lamins, skin keratins, neurofilaments
First discovered as keratins of hair
Not essential for eukaryotic life - IFs missing in insects and fungi- why?

Term

 

 

 

Intermediate Filament Structure

Definition

Although diverse, intermediate filaments share common structure: globular amino-terminal domain, central alpha helical rod domain, COOH globular domain
Fold into coiled coil dimers.
Some Ifs form homopolymeric filaments
(vimentin, desmin)
Others form heteropolymeric filaments
(keratins neurofilaments

Term

 

 

 

Intermediate Filaments are Apolar or Polar

Definition

Apolar!

 

Actin Filaments and Microtubules are Polar!

Term

 

 

 

Intermediate Filament Function

Definition

Mechanical- Protection of cells/tissues from mechanical and non mechanical stresses.  Proper distribution of organelles.

Non mechanical--Sensors for regulating cell growth, division, and cell death

Term

 

 

 

mutations in K5 and K14 

Definition

Epidermolysis bullosa simplex (EBS), 


cause reaction with desmesomes and hemidesmesomes to be less strong

Term

 

 

 

mutations in K1 and K10

Definition

cause epidermolytic hyperkeratosis(EH)

Term




Laminophathies

Definition

Defects in LMNA (gene encoding Lamin A&C) implicated in 12 disorders

Term

 

Hutchinson-Gilford Progeria syndrome

Definition

normal development for 6-12 months followed by failure to gain wt and slow growth.


Average life expectancy is 13 years with ~90% of patients dying from atheroslcerosis


most HG patients have mutation that activates a cryptic slpice site that result in in 50 amino acid frame deletion of Lamin A which accumulates and become Progerin

Term



Intermediate filaments vs Actin and Microtubules

Definition

subunit structure- coiled-coil building block vs globular building block
polarity- apolar IF vs polar actin filaments and microtubules
nucleotide binding
diversity of proteins vs diversity of functions
Essential for life - actin and tubulin genes are essential for life, IF genes are not

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