May act as a cell-binding protein. Trimer or homomer. Secreted into as a 135 kDa monomer under reducing conditions and as a homotrimer under non-reducing conditions. Expressed in skin, intestine, sternum, brain and kidney. Lower expression is also observed in heart, lung, sciatic nerve, dorsal root ganglia, peripheral nerves and calvaria of newborn mice and in intestine and brain of adult mice. Found in basement membrane surrounding a particular subset of Schwann cells in adult sciatic nerve. Major expression in dorsal root ganglia and peripheral nerves, with small amounts in connective tissues like calvaria and skin. Belongs to the VWA-containing collagen family.