The assembly state of the intermediate filament proteins desmin and glial fibrillary acidic protein at low ionic strength

Abstract

The low ionic strength structures of the type III intermediate filament (IF) proteins desmin and glial fibrillary acidic protein (GFAP) have been studied by transient electric birefringence measurements. Flexible dimers with a length of around 45 nm, particles with a length of 68 +/- 6 nm (presumably tetramers and hexamers) and larger aggregates of 108 +/- 19 nm are found. GFAP has an increased tendency to aggregate upon lowering of the pH. The aggregation state of desmin does not change in the pH range studied. The results are compared with previous results on vimentin.