[1] Collagen: An overview

This chapter outlines the development of information concerning the molecular heterogeneity of collagen. This heterogeneity is ultimately determined by the genome, but is amplified by posttranslational events that allow for wide variations in the extent to which different types of procollagen molecules are processed prior to incorporation into their respective fibrous elements. The extent to which procollagen molecules are processed more than likely specifies the general properties of the fibrous elements formed at any given site. The general properties of the fibrous elements may, in turn, be of great importance with respect to specific interactions with other matrix macromolecules as well as with cells. The information concerning the distribution and localization of the collagens in various connective tissues strongly support the notion that each of the collagens has evolved to accommodate specific physiological requirements of organisms of increasing complexity. In this regard, it is likely that the multiple genes for collagen synthesis represent an informational multigene family, or perhaps a number of families, the existence of which allows the selective synthesis of discrete, albeit functionally related, proteins.