Cell ≫ 세포골격 ≫ ECM

세포 - laminins

세포골격, ECM
- 증점(단순)다당류 , 복합다당류
- 세포는 Fiber 덩어리다 , 세포는 콜라겐 덩어리다
- 콜라겐 Collagen ,  콜라겐 조성 및 합성과정
- 엘라스틴 elastin,  Proteoglycan
- Fibronectin,  Laminins
- Integrins,  Cadherins

1. found primarily in the basal laminae
   a. basal laminae (BL) = specialized thin (50 nm)
                      sheets of ECM material almost always found
                      separating epithelial cell layers and underlying connective tissue
  b. functions of BL
                       -in kidneys (see EM 1, 2, 3)
                               -BL = ECM secreted by the capillary endothelial cells
                               -BL helps maintain tissue organization
                                      -strong, tough material
                                      -very highly crosslinked
                                      -crosslinks other ECM components
                                               -collagen,  cell surface receptors,  heparin
                               -BL serves as a very fine molecular sieve
                                      -blood in capillaries under pressure
                                      -fluids flow out of capillaries, through BL and collected in Bowmans Space    
                                      -BL allows small molecules
                                       (eg: less than 6000 Da)  in blood
                                       to pass, but prevents large molecules
                                       (eg: proteins) from entering urine
                                      -Clinical Symptoms of malfunctioning BL
                                             -proteinuria = protein in urine
                                                      -holes in BL too large
                                             -hematuria = blood elements in urine
                                                      -holes in BL way too large!!!
                       -in gut
                              -BL helps maintain tissue organization
                              -BL prevents connective tissue cells from
                               moving out into epithelial cells
                             -BUT, BL does allow white blood cells to pass
                               through to fight infection
2. laminin is key adhesive protein of BL
3.  properties of laminin
                   a. very large protein   -MW about 850,000 daltons
                   b. three long polypeptides  -alpha, beta 1 and beta 2
                   c. held together by disulfide bonds
                   d. structure of laminin
                   e. multiple domains with binding sites
                         -binding sites for:
                                - type IV collagen, heparin, heparin sulfate
                                -laminin receptor proteins on surface of PM
                                       -transmembrane integral proteins
                                         with specific binding sites for laminin
                                       -integrins (see below)
                    f.  serves as a main crosslinking molecule in BL
                    g.  serves as a bridging molecule
                          -links cell's PM  to basal lamina
                          -helps hold cells together
                          -helps hold the BL together