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Cell migration entails protrusion of lamellipodia, densely packed networks of actin filaments at the cell front. Filaments are generated by nucleation, likely mediated by Arp2/3 complex and its activator Scar/WAVE. It is unclear whether formins contribute to lamellipodial actin filament nucleation or serve as elongators of filaments nucleated by Arp2/3(More)
Formin proteins were recognized as effectors of Rho GTPases some 15 years ago. They contribute to different cellular actin cytoskeleton structures by their ability to polymerize straight actin filaments at the barbed end. While not all formins necessarily interact with Rho GTPases, a subgroup of mammalian formins, termed Diaphanous-related formins or DRFs,(More)
Formins are actin polymerization factors that are known to nucleate and elongate actin filaments at the barbed end. In the present study we show that human FHOD1 lacks actin nucleation and elongation capacity, but acts as an actin bundling factor with capping activity toward the filament barbed end. Constitutively active FHOD1 associates with actin(More)
Actin cytoskeleton remodeling, which drives changes in cell shape and motility, is orchestrated by a coordinated control of polarized assembly of actin filaments. Signal responsive, membrane-bound protein machineries initiate and regulate polarized growth of actin filaments by mediating transient links with their barbed ends, which elongate from(More)
Intermediate filaments (IFs) reconstituted from purified, delipidated vimentin and desmin as well as respective protofilaments were subjected to degradation by Ca2+-activated neutral thiol proteinase, thrombin and lysine-specific endoproteinase Lys-C, respectively. The breakdown products were analyzed by SDS-polyacrylamide gel electrophoresis and negative(More)
The interaction of intermediate filaments prepared from pure, delipidated vimentin with vesicles obtained from Ehrlich ascites tumor (EAT) cell lipids was studied employing sucrose density gradient centrifugation in combination with electron microscopy. In negative stain electron microscopy, preformed vimentin filaments were seen in lateral association with(More)
Neurofibromatosis type 1 (NF1) is a common genetic disorder caused by alterations in the tumor suppressor gene NF1. Clinical manifestations include various neural crest derived tumors, pigmentation anomalies, bone deformations, and learning disabilities. NF1 encodes the Ras specific GTPase activating protein (RasGAP) neurofibromin, of which the central(More)
Based on the finding that vimentin isolated and purified from cultured mammalian cells is heavily contaminated by neutral lipids, the binding of a series of radioactively labeled nonpolar lipids to pure, delipidated vimentin was investigated. Employing gel permeation chromatography of the complexes on Sephacryl S-300, cholesterol, cholesteryl fatty acid(More)
Sucrose gradient analysis of reaction products obtained from non-epithelial intermediate filament (IF) subunit proteins and a mixture of supercoiled, relaxed and linearized plasmid pBR322 DNA at low ionic strength revealed that limited amounts of these polypeptides interacted exclusively with the supercoiled form of the plasmid DNA. These results were(More)
The biological functions of the non-alpha-helical, N- and C-terminal head and tail domains of intermediate filament (IF) proteins are still ill-defined. Previously, it has been shown that the basic, N-terminal head piece of the type III IF protein vimentin is essential for regular IF assembly and that arginine residues within the N-terminus may be involved.(More)