Table 1.

Roles of Extracellular Matrix Constituents

ECM Constituents	Function	Role	Examples
Fibrillar collagens	resist tensile and shearing forces	primarily mechanical	collagen I and III
Elastin	provide recoil and tissue shape memory	primarily mechanical	n/a
Proteoglycans	resist compressive forces, provide some recoil	primarily mechanical	dermatan, heparan, chondroitin sulfates
Small leucine-rich repeat proteins (SLRPs)	matrix fiber assembly	cell- and matrix-interactive	asporin, byglycan, lumican
Non-fibrillar collagens	basement membrane and cartilage	cell- and matrix-interactive	collagens II and IV
Smaller collagens	bind cells to other matrix molecules	cell- and matrix-interactive	collagens V, VI, and XII
Basement membrane glycoproteins	bind cells to substrate	cell- and matrix-interactive	laminin, nidogen, fibronectin
Growth factor binding proteins	modulate bioavailability	cell- and matrix-interactive	TGFβ and IGF

Primarily mechanical roles are typically widely distributed and less idiotypic. Cell- and matrix-interactive roles are typically more cell idiotypic.