Collagen in the extracellular matrix

Kielty, C.M., Hopkinson, 1., Grant, M.E. Collagen structure, assembly and organization in the extracellular matrix. In Connective Tissue and its Heritable Disorders Wiley-Liss, Chichester, pp. 103-147, 1993. 

The same ceUs that secrete collagen also secrete fi-bronectin, a large glycoprotein present on cell surfaces, in the extracellular matrix, and in blood (see below). Fi-bronectin binds to aggregating precollagen fibers and alters the kinetics of fiber formation in the pericellular matrix. Associated with fibronectin and procollagen in... 

Type I collagen can interact with various other molecules in the extracellular matrix and on the cell surface. Cell receptors of type I collagen have been identified and include the heterodimeric integrin family receptors, ctl, 0 2, olO, and ol 1, especially o2/3l, the receptor tyrosine kinase discoidin domain receptor (DDR), and the heparan sulfate membrane proteoglycan syndecan family... 

Fibril-associated collagens Types IX and XII bind to the surface of collagen fibrils, linking these fibrils to one another and to other components in the extracellular matrix (see Figure 4.2). 

Kielty, C. M., and Grant, M. E. (2002). The Collagen Family Structure Assembly and Organization in the Extracellular Matrix. In Connective Tissue and its Heritable Disorders, (P. M. Royce andB. Steinmann, Eds.), pp. 159-222. Wiley-Liss, New York. 

There are several self-assembling macromolecules that are of interest to us in this text. They include (1) collagen, the primary structural material found in the extracellular matrix (2) actin, a component of the cell cytoskeleton that is involved in cell locomotion and in formation of the thin filaments of muscle (3) microtubules, which are involved in cell mitosis, movement, and organelle movement and finally (4) fibrinogen, which forms fibrin networks that minimize bleeding from cut vessels. Self-assembly is important in these systems because the function of these macromolecules can be modified via processes that increase the molecular axial ratio and hence decrease the solubility. 

Collagen is the major insoluble fibrous protein in the extracellular matrix and in connective tissue 80-90% of the collagen in the body consists of types 1, It and 111 (Table 12.2). The collagen superfamily consists of at least 20 collagen types, with as many as 38 distinct polypeptide chains and more than 15 additional proteins that have collagen-like domains. 

Kiehy CM, Hopkinson I, Grant ME Collagen The collagen familiy Structure, assembly, and organization in the extracellular matrix. In Royce PM, Steinman B (eds) Conncective tissue and its heritable disorders. Wiley-Liss, New York 103-147,1993... 

An increase in the extracellular matrix due to collagens, elastin, proteoglycans, glycoproteins, etc. also produces various degrees of hepatomegaly. 

C. Collagen refers to a group of similar structural proteins that are found, for example, in the extracellular matrix, the vitreous humor of the eye, and in bone and cartilage. 

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