Figure 22-26. Structure of cartilage proteoglycan aggregate.
Figure 22-26. Structure of cartilage proteoglycan aggregate.

Figure 22-26Structure of cartilage proteoglycan aggregate

(a) Electron micrograph of a proteoglycan aggregate from fetal bovine epiphyseal cartilage. Aggrecan core proteins are bound at ≈40-nm intervals to a molecule of hyaluronan. Numerous keratan sulfate and chondroitin sulfate chains are attached to the aggrecan core proteins. (b) Diagram of detailed structure of an aggrecan monomer. The N-terminal domain of the core protein binds to a hyaluronan (HA) molecule. Binding is facilitated by a link protein, which binds to both the hyaluronan disaccharide and the aggrecan core protein. Each aggrecan core protein has 127 Ser-Gly sequences at which the glycosaminoglycan chains are added; 30 short keratan sulfate chains and 97 longer chondroitin sulfate chains are added to each core protein molecule in aggrecan. [Part (a) from J. A. Buckwalter and L. Rosenberg, 1983, Coll. Rel. Res. 3:489; courtesy of L. Rosenberg.]

From: Section 22.4, Noncollagen Components of the Extracellular Matrix

Cover of Molecular Cell Biology
Molecular Cell Biology. 4th edition.
Lodish H, Berk A, Zipursky SL, et al.
New York: W. H. Freeman; 2000.
Copyright © 2000, W. H. Freeman and Company.

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