Abstract
Iaminin is the major glycoprotein found in basement membranes, the thin extracellular matrix which underlies all epithelia and surrounds muscle, peripheral nerve and fat cells. It also binds to other components in the matrix (i.e. type IV collagen, heparan sulfate proteoglycan and en&tin) and to itself. As laminin has multiple biological activities, including promotion of cell adhesion, growth, migration, differentiation, neurite outgrowth and tumor metastases, it has been actively studied in order to understand the mechanisms involved in these diverse cellular responses. Major advances have been made in the study of the structure, biological activity and cellular receptors for lamlnin. All three of its chains have been sequenced by complementary DNA (cDNA) cloning in many species, and several biologically active sites have been localized using proteolytic fragments, antibodies and synthetic peptides. This review will cover the recently elucidated structure of this molecule and of related homologous proteins, its biological activity, active sites and cellular receptors.