Browse the corpus

©2013 UpToDate ® Print Email Schematic of the basement membrane (BMZ) zone and intercelllular desmosomal adhesion Intermediate filaments composed of keratin 5 and 14 insert on the keratin (cytoskeletal) linker proteins plectin and BPAG1 (BP230) at the superior aspect of the BMZ. Plectin and BPAG1 interact with transmembrane a6b4 integrin and type XVII collagen (BP180/BPAG2), forming hemidesmosomes that attach basal keratinocytes to the underlying basement membrane. Anchoring filaments jut out below the hemidesmosome and include laminin-332 and laminin-311 that associate with type XVII collagen and a6b4 integrin, but also laminin-511, type IV collagen and nidogen, thereby forming the lamina densa. Anchoring fibrils extend perpendicularly as banded projections from the lamina densa and contain polymeric associations of type VII collagen molecules that intertwine between dermal interstitial collagen fibrils. Type VII collagen triple helices attach the lamina densa to papillary dermis and are critical for the integrity of the epidermal-dermal junction through their ability to bind laminin-332. Intercellular junction is mediated by desmosomes whose intracellular protein components include desmoplakin (interacting with intermediate filament network), plakophilin as well as plakoglobin, the latter which connect to the transmembrane cadherin tails (composed of desmoglein, desmocollin).