The 120 kDa linear IgA disease antigen homolog is an anchoring filament component involved in dermal-epidermal cohesion. Homotrimers of alpha 1(XVII)chains. Interacts (via cytoplasmic region) with ITGB4 (via cytoplasmic region). Interacts (via cytoplasmic region) with DST (via N-terminus). Interacts (via N-terminus) with PLEC. Interacts (via cytoplasmic region) with DSP (By similarity). Localized along the plasma membrane of the hemidesmosome. Upper lamina lucidalhemidesmosome. The intracellular/endo domain is disulfide-linked. Prolines at the third position of the tripeptide repeating unit (G-X-Y) are hydroxylated in some or all of the chains. The ectodomain is shedded from the surface of keratinocytes resulting in a 120-kDa soluble form, also named as 120 kDa linear IgA disease antigen homolog. The shedding is mediated by membrane-bound metalloproteases (By similarity). Defects in COL17A1 are the cause of generalized atrophic benign epidermolysis bullosa. This nonlethal form of junctional epidermolysis bullosa is characterized by life-long blistering of the skin, associated with hair and tooth abnormalities.