Structural features of newly synthesized type VII collagen. (A) Rotary shadowing image of a type VII collagen molecule synthesized and secreted by human keratinocytes in culture. Note the central collagenous domain, flanked by non-collagenous NC-1 and NC-2 sequences. (B) Identification of NC-1 domains at both ends of a type VII collagen dimer molecule, as visualized by a monoclonal anti-type VII collagen antibody in rotary shadowing image. Note that the dimer has an overlapping region of the carboxy-terminal ends of the two molecules, as schematically illustrated in C. (Adapted from Sakai LY, Keene DR, Morris NP, et al. Type VII collagen is a major structural component of anchoring fibrils. J Cell Biol 1986; 103: 1577-86. and Burgeson RE. Type VII collagen, anchoring fibrils, and epidermolysis bullosa. J Invest Dermatol 1993; 101: 252–5., with permission).