Collagens, Suprastructures, and Collagen Fibril Assembly

Extracellular matrices are composed of collagens, proteoglycans, glycosaminoglycans, glycoproteins, and elastin. Extracellular matrix not only serves as structural scaffolds in organs and tissues, but also determines cellular function through cell–matrix interactions. Accordingly, the structures and organization of extracellular matrices are diverse and adapted to tissue-specific function. This chapter focuses on the collagen family. There are 28 different types of collagen that assemble into a variety of supramolecular structures including fibrils, microfibrils, and network-like structures. This chapter begins with a discussion of collagen molecules. This is followed by a definition of the supramolecular structure of different collagen types and their assembly and function within extracellular matrices. A discussion of general mechanistic principles involved in the assembly of collagen-containing suprastructures is presented. Finally, the regulation of tissue-specific collagen fibrillogenesis is used to illustrate how these general principles are applied in different tissues to generate the diversity in extracellular matrix structures and functions observed.