Molecules of the extracellular matrix: potential role of collagens and glycoproteins in intestinal adaptation.

The extracellular matrix plays a fundamental role in modulating cellular growth, differentiation and migration. Therefore it merits major attention in studies of adaptation. The five types of collagen and several extracellular glycoproteins hitherto found in the intestine are biochemically well defined. They form supramolecular complexes and via specific domains interact with integrins, a specialized class of transmembrane glycoproteins. The integrins transfer signals to the cytoskeleton and probably to the nucleus of the cell. The extracellular matrix and its cellular receptors are well orchestrated with several cell types, the immune system and soluble mediators and hormones, thus being indispensable members of a complicated regulatory network operative in adaptation.