The basal lamina contains Collagen Type IV, proteoglycans, and glycoproteins. Laminin is a high molecular weight (850 kDa) oligomer, consisting of three different chains (alpha, beta, and gamma) joined by disulfide bonds. The structure of laminins include two helical domains (I & II) at the COOH-terminal, a laminin IV domain, multiple EGF-like repeats, and a laminin globular domain (G), as well as an N-terminal domain VI. Domains IV and VI are the binding sites for collagen and heparan sulfate, respectively. Several isoforms have been identified for the genes of each chain. Laminin gamma1 (laminin B2) contains 14 glycosylation sites and 12 cysteine repeat domains. The expression of the Laminin subunits is found in the basal lamina of tissues. Here, the protein interacts with other extracellular matrix components to mediate cell attachment, migration and organization during embryonic development.
