Intermediate filaments

Intermediate filaments

1. subunit

   • fibrous protein

2. function

   • provide cellular strength when stretched, toughest, strengthen nuclear envelope

3. location

   • from the nucleus to plasma membrane, connected at desmosomes
   • muscle cells, epithelial cells, along nerve axons for reinforcement and protection

4. structure

   • strong rope like with diameter of 10nm that are elongated fibrous proteins
   • start as a single monomer
     • 2 monomers twist together to form a coiled coil
       • 2 coil coils are staggered and come to form a tetramer-- held together by covalent forces

5. 4 classes

   • keratin filaments: epithelial cells, found throughout the entire cell
   • vimentin and vimentin related filaments: connective tissue, muscle cells, neuroglial cell, they help out the neurofilaments
   • neurofilaments
   • nucclear lamina: in nucleus (nuclear membrane)

6. plectin

   • strengthening protein
     • stabilizes and bind the intermediate filaments

7. problems (outside nucleus)

   • epidermoloysis bullosa simplex: blisters form upon simply touching the skin, involved both intermediate filaments and plectin
   • mutations in plectin alone: can cause the blisters but can also cause muscular dystrophy, neurodegeneration

8. nuclear lamins

   • help the nucleus disassemble during mitosis and break apart the nuclear membrane

9. progeria

   • loss of lamins that leads to an incomplete cell division