Proteins bound to poly(A) sequences of polyribosomes from germinating wheat embryos

A preparation of purified polyribosomes was isolated from wheat embryos germinating for 1 h with [3H]adenosine. Treatment of polyribosomes with pancreatic ribonuclease leads to the liberation of particles containing poly(A) sequences. Poly(A)-containing complexes show a heterogeneous distribution in the region 8--15 S. The ability of 8--15 S material to be absorbed to membrane filters under the conditions of low ionic strength and its sensitivity to pronase indicate that poly(A) sequences in polyribosomes are associated with protein. Analysis of this protein by electrophoresis in a polyacrylamide gel demonstrates the presence of two polypeptides with the molecular weights equal to 86,000 and 52,000.