Interaction of DNA with cytoplasmic particles: I. Formation of a cytoplasmic particle-DNA complex

(1) Evidence is presented that cytoplasmic particles, isolated from calfthymus cells, rat-liver cells and rabbit reticulocytes, possess a potential ability to bind DNA at a certain site and to form a cytoplasmic particle-DNA complex which is starch-electrophoretically and centrifugally separable from particles and DNA.(2) Chemical analysis of the complex formed revealed that the number of cytoplasmic particles which are capable of binding to one molecule of DNA is not markedly different from the number of nuclear ribosomal particles.(3) The binding sites appeared to be specific for only DNA and mRNA. However, the relative affinities for DNA and for poly (U) at a particular site differ greatly from those at other sites.(4) The differential affinities for certain classes of informational macromolecules on the particle are discussed. The possibility of a correlation with ribosomal differentiation is considered.