Particle weights of active ribosomal subunits from Neurospora crassa

Abstract

Particle weights of ribosomes and ribosomal subunits from Neurospora crassa have been calculated from the mol. wt of the rRNA and the relative RNA contents of the particles (as determined from buoyant density in CsCl). The high-salt washed monomeric ribosomes (3.95 · 10 6–3.98 · 10 6 daltons) are identical in size to those of higher plants. Functionally active large and small subunits derived from “run-off” ribosomes of Neurospora exhibit molecular weights of 2.50 · 10 6 and 1.55 · 10 6, similar to those isolated from several green plants. It is suggested that the sizes of both ribosomal subunits have been largely conserved in the plant kingdom, and that a change in the size of the large subunits has occurred only in animals, parallel with the increase in size of the major rRNA component.