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 homolog is an anchoring filament component involved in dermal-epidermal cohesion. Homotrimers of alpha 1(XVII)chains. Localized along the plasma membrane of the hemidesmosome. Cornea specific. 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).