Characterization of translational-control ribonucleic acid isolated from embryonic chick muscle.

Myosin heavy chain (MHC) mRNP particles have been purified from 13-day chick embryonic skeletal muscle by a combination of sucrose density gradient centrifugation and metrizamide buoyant density centrifugation. Associated with the mRNPs are at least three distinct low molecular weight RNA molecules including translational-control RNA (tcRNA). This particular RNA contains 102 nucleotides and is uridine and guanine rich, and its nucleotide sequence has been determined. tcRNA102 is capable of inhibiting the translation of the mRNAs with which it is associated upon preincubation in stoichiometric amounts. Under these conditions, endogenous reticulocyte mRNA is not inhibited. Under appropriate salt and temperature conditions, tcRNA102 is capable of reassociating with myosin heavy chain (MHC) mRNA, thus altering the sedimentation characteristics of the mRNA. This suggests that the mRNA-tcRNA102 interactions alter the secondary structure of the mRNA. In addition, tcRNA102 does not associate with ribosomal RNA or globin mRNA, suggesting that some degree of specificity is involved with the RNA-RNA interactions.