Ribosome Heterogeneity in Plant and Animal Organisms. Its Relationship to Ribosomal Ambiguity and to Ribosome Evolution

Abstract

Abstract The data presented and discussed in this report summarize evidence showing that ribosomes isolated from several eucaryotic (plant and animal) organisms exhibit ample variations of the composition of their protein moiety and that the degree of dissimilarity correlates with the degree of taxonomic kinship of the organisms from which the ribosomes were derived. They also provide evidence that (a) the 80-S ribosomes isolated from the cytoplasmic matrix of higher plants and yeast and the 70-S ribosomes derived from both chloroplasts and mitochondria are endowed with highly dissimilar protein complements, (b) the organellar (67-S) ribosomes derived from the chloroplasts of more or less distantly related plants exhibit a greater degree of dissimilarity than the corresponding 78-S ribosomes derived from the extra-chloroplast, extramitochondrial portion of the cytoplasm, i.e., in distant organisms the protein composition of cytoplasmic ribosomes tends to be more congruent than that of organellar ribosomes...