These structures contain the extracellular portions of collagen XVII (BP180) and alpha-6-beta-4 (α-6-β-4) integrin. In addition, anchoring filaments contain the molecules ‘laminin 5’ and ‘laminin 6’. Similar to all members of the family of laminin proteins, laminin 5 is a large heterotrimeric molecule, containing α-3, β-3, and g-2 chains. Laminin 5 forms a disulfide-bonded attachment to laminin 6, the other known anchoring filament laminin, which contains α-3, β-1, and g-1 chains. Laminin 5 also forms a strong association with type VII collagen, which serves to connect anchoring filaments with anchoring fibrils.