May play a role in the integrity of hemidesmosome and the attachment of basal keratinocytes to the underlying basement membrane. The 120 kDa linear IgA disease antigen is an anchoring filament component involved in dermal-epidermal cohesion. Is the target of linear IgA bullous dermatosis autoantibodies. Homotrimers of alpha 1(XVII)chains. Interacts (via cytoplasmic region) with ITGB4 (via cytoplasmic region). Interacts (via cytoplasmic region) with DST isoform 3 (via N-terminus). Interacts (via N-terminus) with PLEC. Interacts (via cytoplasmic region) with DSP. Localized along the plasma membrane of the hemidesmosome. Exclusively localized to anchoring filaments. Localized to the epidermal side of split skin. Localized in the lamina lucida beneath the hemidesmosomes. Detected in skin (PubMed:8618013). In the cornea, it is detected in the epithelial basement membrane, the epithelial cells, and at a lower level in stromal cells (at protein level) (PubMed:25676728). Stratified squamous epithelia. Found in hemidesmosomes. Expressed in cornea, oral mucosa, esophagus, intestine, kidney collecting ducts, ureter, bladder, urethra and thymus but is absent in lung, blood vessels, skeletal muscle and nerves. 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. The shedding is mediated by membrane-bound metalloproteases. This cleavage is inhibited by phosphorylation at Ser-544. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Both the 120 kDa linear IgA disease antigen and the 97 kDa linear IgA disease antigen of COL17A1, represent major antigenic targets of autoantibodies in patients with linear IgA disease (LAD). LAD is a subepidermal blistering disorder characterized by tissue-bound and circulating IgA autoantibodies to the dermal-epidermal junction. These IgA autoantibodies preferentially react with 97 and the 120 kDa forms, but not with the full-length COL17A1, suggesting that the cleavage of the ectodomain generates novel autoantigenic epitopes. Extended N-terminus. Contaminating sequence. Potential poly-A sequence.