[Low-molecular RNA subcellular localization and its binding strength with cellular structures]

Some fractions of low molecular weight (LMW) nuclear RNAs were shown to be present in the cytoplasm of rat liver cells. In addition to known 4S tRNA, 5S and 5,8S rRNAs U3 and 8S1 LMW nuclear RNAs, 8SII and 8SIII LMW RNAs have been detected in RNA preparations of free total and membrane-bound polysomes. The U3 and 8SI polysoma I RNAs seem to be associated with high molecular weight polysomal RNA. Using thermal phenol fractionation, that some LMW RNAs were shown to be slightly bound to the cellular structures whereas some others are bound more tightly. Considerable amounts of LMW RNAs are tightly bound to the chromosome-nucleolar apparatus. They can be extracted only at 85 degrees C. The data presented are discussed with regard to LMW nuclear and polysomal RNAs functions.