A novel protein (Fbf-1) that binds to CD95/APO-1/FAS and shows sequence similarity to trichohyalin and plectin

The Fas/Apo-1/CD95 cell surface receptor belongs to the TNF receptor family of cell death inducing molecules. A number of cytosolic adapter proteins t hat mediate signal transduction of CD95 have been characterized, but some f eatures of the molecular mechanisms of CD95-induced cell death remain elusi ve. We describe here a novel protein that can interact with the cytosolic d omain of the murine CD95 receptor in a yeast two-hybrid assay. This novel p rotein was termed Fbf-1 for Fas binding factor and bears no sequence simila rity to the known CD95 adapter proteins. Fbf-1 is 1173 aa long and has a th eoretical. molecular weight of around 130 kDa. The protein is expressed in a wide variety of tissues and is localized in the cytoplasm, Fbf-1 is a ver y hydrophilic protein, highly conserved between mouse and human and bears a carboxyterminal leucine heptad repeat reminiscent of leucine zipper protei n interaction domains, In addition, it shows sequence similarity to trichoh yalin and plectin pointing to a function as a structural protein. (C) 2000 Elsevier Science B.V. All rights reserved.