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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
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
Has dozens of
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
attached to long
substance. proteoglycans attach loosely to HYALURONAN
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.
- Spring '14