Cell ¡í ¼¼Æ÷°ñ°Ý ¡í ECM
¼¼Æ÷ - laminins
¼¼Æ÷°ñ°Ý, ECM
- ÁõÁ¡(´Ü¼ø)´Ù´ç·ù , º¹ÇÕ´Ù´ç·ù
- ¼¼Æ÷´Â Fiber µ¢¾î¸®´Ù , ¼¼Æ÷´Â Äݶó°Õ µ¢¾î¸®´Ù
- Äݶó°Õ Collagen , Äݶó°Õ Á¶¼º ¹× ÇÕ¼º°úÁ¤
- ¿¤¶ó½ºÆ¾ 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