Fig. 1. Schematic representation of collagen XVII and the epitope regions recognized by antibodies. The full-length collagen XVII is a type II integral transmembrane protein, which is cleaved to yield a soluble ectodomain. White bars, collagenous sequences; light gray bars, non-collagenous sequences; black line, the cell plasma membrane. Dark gray bars, epitope regions of the domain-specific antibodies. Endo-2 recognizes the intracellular domain, NC-16A the juxtamembranous extracellular NC16a-domain, and Ecto-1 (Schäcke et al., 1998) and Ecto-5 the distal C-terminus of the molecule. The lower panel shows immunoblots of keratinocyte cell layer (C) and media (M) with the above antibodies. Ecto-1, Ecto-5, and NC16A recognized both the 180 kDa full-length collagen XVII and the 120 kDa soluble ectodomain. In contrast, Endo-2 recognized only full-length collagen XVII.