Synthesis of Lens Protein in vitro

Poly U‐directed stimulation of preincubated calf lens ribosomes revealed that these particles from a mammalian source have a phenylalanine incorporation ability comparable to the Escherichia coli system. A search was made for optimal conditions. After variation of the magnesium concentration during preincubation two levels of maximal incorporation were observed. The region of highest relative stimulation did not coincide with these maxima. Preincubation under conditions of optimal amino acid incorporation yields 80S monomers and to a lesser extent 120S particles. No smaller units or breakdown products were observed in the analytical ultracentrifuge. Such particles could be demonstrated after prolonged dialysis of either polysomes or 80S monomers against 0.1 mM MgCI2. Their sedimentation coefficients were 50 S and 30 S respectively but not 60 and 40 S.