An Introduction to Proteoglycans and Their Localization

Proteoglycans comprise a core protein to which one or more glycosaminoglycan chains arecovalently attached. Although a small number of proteins have the capacity to beglycanated and become proteoglycans, it is now realized that these macromolecules have arange of functions, dependent on type and in vivo location, and have important roles ininvertebrate and vertebrate development, maintenance, and tissue repair. Many biologicallypotent small proteins can bind glycosaminoglycan chains as a key part of their function inthe extracellular matrix, at the cell surface, and also in some intracellular locations.Therefore, the participation of proteoglycans in disease is receiving increased attention.In this short review, proteoglycan structure, function, and localizations are summarized,with reference to accompanying reviews in this issue as well as other recent literature.Included are some remarks on proteoglycan and glycosaminoglycan localization techniques,with reference to the special physicochemical properties of these complex molecules.