EXTRACELLULAR-MATRIX AND ITS RECEPTORS DURING DEVELOPMENT

Extracellular matrix (ECM) components are essential for morphogenesis of virtually all tissues. The ECM interacts with the cell surface by b inding to specific receptors. The first family of receptors for the EC M that was identified was the integrin family. Integrins are composed of an a and a Q-chain, both of which are single pass transmembrane pro teins. In muscle cells the dystroglycan complex forms another importan t receptor system for ECM. It is a complex composed of many proteins. Recent studies have shown that dystroglycan is expressed by embryonic epithelial cells as well. The nature of constituents of the dystroglyc an complex is well known for muscle, whereas the detailed composition of the dystroglycan complex in embryonic epithelium is not yet well kn own. We here review the evidence that binding of ECM to integrins and the dystroglycan complex could be essential for muscle and epithelial cell development and function. It is likely that integrins and the dys troglycan complex have distinct roles during development. It will be a n interesting task to study the signal transduction pathways elicited by the interactions between ECM and the two receptor systems during mu scle and epithelial morphogenesis.