HEMIDESMOSOMES AND THEIR UNIQUE TRANSMEMBRANE PROTEIN BP180

Hemidesmosomes are adhesion complexes responsible for linking keratin intermediate filaments of stratified and complex epithelia to componen ts of the extracellular matrix such as collagen fibrils. Over the past several years, it has become clear that there are at least five hemid esmosomal proteins, including HD1/plectin and BP230 as cytoplasmic pla que proteins and integrin alpha 6 beta 4 and BP180 as transmembrane pr oteins. Among them, BP180 is unique as a transmembrane protein because of its collagenous extracellular domain. Recent biochemical and ultra structural analyses have revealed its molecular configuration and natu re as a major component of anchoring filaments connecting hemidesmosom es to the basement membrane. These results indicate that BP180 is a ne w type of adhesion receptor. In addition to biochemical analyses of th ese hemidesmosomal proteins, recent studies on patients with inherited skin blistering diseases and on knockout mice have demonstrated roles in hemidesmosome formation and stabilization, as well as unexpected, novel functions. (C) 1998 Wiley-Liss. Inc.