Study on protein content of rabbit reticulocyte ribosomal subunits: correlation with functional activity.

The correlation between chemical composition (protein content) of native and derived ribosomal subunits and their activity in a cell-free system, programmed with haemoglobin messenger RNA, has been investigated. On the basis of isodensity sedimentation of formaldehyde fixed particles in CsC1 and of two-dimensional gel electrophoresis of ribosomal proteins, it appears that the native ribosomal subparticles contain a large protein complement than the derived subparticles and, correspondingly, they are less dependent on an external supply of initiation factors for haemoglobin synthesis in vitro.