STRUCTURE AND RNA-CONTENT OF THE PROSOMES

Duck erythroblasts prosomes were analysed by small angle neutron scatt ering (SANS), dynamic light scattering and (cryo-)electron microscopy. A molecular weight of approximately 720,000 +/- 50,000, a radius of g yration of 64 +/- 2 angstrom and a hydrodynamic radius of approximatel y 86 angstrom were obtained. Electron micrographs show a hollow cylind er-like particle with a diameter of 120 angstrom, a height of 170 angs trom and a diameter of 40 angstrom for the cavity, built of four discs , the two outer ones being more pronounced than those in the center. R esults from SANS indicate less then 5% of RNA in the purified prosomes , but nuclease protection assays confirm its presence.