The collagens, proteoglycans, and glycoproteins of the extracellular matrix (ECM) are a diverse collection of macromolecules, heterogeneous in size, structure, and function. However, their primary structures have revealed that their polypeptide components are frequently comprised of a series of sequence repeats or “modules” (1 ). This mosaic nature of ECM macromolecules permits their properties to be analyzed by a “dissection” strategy (2 ), where protein fragments generated by proteolysis, chemical synthesis, or recombinant expression are employed in structural and functional investigations.
