The Isolation and Purification of Rapidly Labeled Polysome-bound Ribonucleic Acid on Polythymidylate Cellulose

The polyadenylate (poly(A)) sequences of about 150 nucleotides found among all size classes of the pulse-labeled RNA bound to HeLa polysomes which is thought to be messenger RNA (mRNA) provide a basis for the purification of such RNA by hybridization to polythymidylate (poly(T)) cellulose. Poly(A) sequences comprised 15% of the RNA from polysomes which was bound to poly(T) cellulose. This RNA when released from the cellulose sedimented in sucrose gradients as a heterogeneous population with sedimentation velocities ranging from 6 S to more than 30 S with a maximum of about 18 S. A similar population of RNA molecules was also purified on poly(T) cellulose from cytoplasmic components sedimenting more slowly than polyribosomes.