COLLAGENS AND LAMININS - WHICH MESSAGES FOR WHICH CELLS

Cells in animal tissues are in contact with a structured set of well-d efined proteins that constitute the extracellular matrix. Among these proteins, collagens are ubiquitous in distribution, whereas laminins a re found only in basement membranes. In addition to their structural r ole, collagens and laminins convey messages to cells. A discussion is presented of the structure and diversity of collagens (about 20 types) and laminins (about 12 types). The nature of the cell receptors invol ved in message delivery (integrins-and non-integrins) and the mechanis ms possibly responsible for signal transduction are reviewed.