Ribosome-associated ribonucleases from six-day larvae of the insect Ceratitis capitata.

A 34 kDa, poly(U) and poly(C)-specific ribonuclease, is shown to be tightly bound on purified polysomes from six-day-old larvae of the insect Ceratitis capitata. High salt treatment (400 mM KCl) is necessary to release it completely from the polysomes. Removal of the RNase does not disrupt the structure of the ribosomes, as shown by centrifugation on sucrose gradients and poly U directed polyphenylalanine synthesis.