major components of ground substance are sort of

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Unformatted text preview: ffusion of nutrients, wastes, etc. •  Facilitates cell migration through CT •  Certain components bind and sequester polypeptide growth factors (which stimulate cell cycling when they bind their cell surface receptors.) Major components of ground substance are Sort of like polysaccs, but contain Nitrogen as well….. glycosaminoglycans (GAGs), of 2 general kinds: 1) nonsulfated: hyaluronic acid: a long polymer of repeating disaccharide units that is synthesized by an enzyme complex in the cell membrane of many cells. 2) sulfated: chondroitin sulfate dermatan sulfate heparan sulfate keratan sulfate The sulfated GAGs are much shorter than HA and are covalently linked to “core proteins” during rER/Golgi synthesis/processing to make large proteoglycans. After secretion the core proteins bind hyaluronic acid via “link proteins” to form a huge macromolecular complex in the ECM (next figure). Nonsulfated -- super hydrophilic -- bind water -- ? MUCH shorter than the nonsulfated -- made in GOLGI, already covalently bound to PROTEINS coming off of rough ER -- these proteins act as "core", many GAGs get attached.. This network of protein+GAGs makes up PROTEOGLYCAN. Has dozens of sulfated GAGs attached to CORE PROTEIN. Can see in EM. Proteoglycans (a) are bound to polymers of hyaluronic acid and fill the ground substance, with many glycoproteins (b) also present which bind fibers and cells. These secreted, outside of cell, these Fig. 5-17 This helps keep cells apart? Proteoglycans (non-sulf) attached to long Hyaluronan (sulf), form ground substance. proteoglycans attach loosely to HYALURONAN (nonsulfanated GAGs). SUPER WATERY, DOESN'T STAIN WELL, MAKES UP A SUPER JEL-LIKE GROUND SUBSTANCE TO WHICH GROWTH FACTORS IN ECM CAN ATTACH!!!!!!!! DOESN'T STAIN. TEM of ECM: collagen fibers (C), elastic (E), fibroblasts (F). The poorly defined material is the “ground substance” rich in water and proteoglycans. Fig. 5-16 Multiadhesive glycoproteins in ECM bind to collagen and proteoglycans, and also to integrins in cell mem...
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This document was uploaded on 02/04/2014.

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