Binding to cells via a high affinity receptor, laminin is thought to mediate the attachment, migration and organization of cells into tissues during embryonic development by interacting with other extracellular matrix components. Activates presynaptic signaling involving integrin alpha-PS3/beta-nu and Fak to suppress neuromuscular junction (NMJ) growth during larval development and during low crawling activity, but not during higher-crawling conditions. Mediates, together with integrin alpha-PS3/beta-nu, glutamate receptor-modulated NMJ growth. Laminin is a complex glycoprotein, consisting of three different polypeptide chains (alpha, beta, gamma), which are bound to each other by disulfide bonds into a cross-shaped molecule comprising one long and three short arms with globules at each end. Major component of basement membranes. At neuromucular junctions, localizes in synaptic clefts of peri-active zones and in subsynaptic reticula. Newly formed mesoderm and later prominently expressed in hemocytes, which also synthesize collagen IV. Expressed in muscles. During morphogenesis, mostly in embryo development at 10-12 hours. The alpha-helical domains I and II are thought to interact with other laminin chains to form a coiled coil structure. Domains VI, IV and G are globular. Flies show late embryonic lethality. Certain partial loss-of-function mutations give raise to escaper adults, which have rough eyes associated with changes in cell fate and pattern, misshappen legs and defects in wing structure.