Bio exam 3

  1. what protein makes up 10-20% of protein mass
  2. characteristics of collagen
    • very stable 
    • contains glycine, proline, and hydroxyproline
    • 42 exons, repeats of GXY
    • left handed helix, glycines on one side
    • 3 single helixes form right helix with prolines on outside
  3. translation of collagen
    • insert preprocollagen in ER during translation
    • N-terminal sequence is cleaved -->procollagen
    • procollagen entirely unfolded
  4. post-translational modifications to Collagen
    • proline hydroxylases on Y prolines, uses cofactor ascorbic acid
    • glycosylation on lysines- adds gal or glu-gal
  5. Structure of 3 unfolded propeptides
    • a c-terminal globular peptide connected to an alpha chain
    • the three zip up from C to N-terminus
  6. benefit of C to n zip up of collagen
    • prevents non-specific disorder assembly
    • sets register
  7. what happens as zipper binds the three alpha helices together
    polypeptide isomerase converts all prolines to trans
  8. rate limiting step of collagen zip up
    polypeptide isomerase
  9. how is procollagen transported out of Golgi
    special variance of COPII vesicles transfer it outside of membrane
  10. what is the final step to make a mature collagen trimer
    matrix metallo protease cleaves C-terminal propeptide, uses Zn ion
  11. function of lysyl oxidase
    crosslinks various lysines between 2 trimers to strengthen whole tissue
  12. Elastic Fibers
    rubbery, made from 3 components(Elastin, Fibrillin, something else)
  13. Elastin characteristics
    90% of filter biomass, alpha helix connected to alpha helix, flexible, long and relatively unstructured
  14. Fibrillin
    multiple globular domains in a pattern with flexibility, long, and relatively unstructured
  15. Fibrillin and disease
    faulty fibrillin results in Marfan Syndrome
  16. GAGs
    Glycosaminoglycans - long polysaccharide comprised of dozens to hundreds repeats of a disaccharide
  17. where are GAGs produced
    in the golgi
  18. proteoglycans
    proteins with GAGs on it
  19. Structure of GAGs and Proteoglycans
    large, hydrophillic, charged and bind large quantities of water, mechanically labile structure, not strong
  20. ex. of PG
    in synovial fluid used to lubricate joints, mucus molecules in membranes
  21. ex. of GAG
    collagen GAGS is vitreous humor of the eye
  22. Adhesive glycoproteins ex.
    fibronectin-multiple families large molecules ~235 Da, forms haro dimer
  23. what does fibronectin bind to
    collagens, fibrins, and other PG
  24. what does fibronectin contain
    specific RGD sequence - (arg, gly, asp) bind to integrins
  25. what are integrins
    cell surface receptors that bind to RGD sequence of fibronectin
  26. What is the Basal Lamina
    thin sheet that surrounds muscle and peripheral nerve tissue and lies underneath and provides filtration under kidney
  27. components of basal lamina
    laminin and collagen IV
  28. structure of laminin
    a heterotrimer w/ unique forms a 2-D sheets secreted by epithelium itself and muscle cells
  29. How do cancer cells metastasize
    • cells have upregulation mutations that increase matrix metalloproteases
    • that digest EC and move and rebuild it as they move
  30. what determines if cells migrate/crawl
    density of matrix, not too low or high, just right in the middle

    and CAMS
  31. common case for breast cancer and EC matrix
    collagen density is often ideal for metastasis
  32. Cell Adhesion Molecules (CAMs)
    • 6 families of molecules
    • invidual weak interactions- high avidity
    • involved in information processing, send signals to the cytoskeleton, and signal transduction
  33. 3 types of CAMs
    IgCam, Cadherin, Integrins
Card Set
Bio exam 3
part 2