Ribonucleic acid code words in wheat germ.

An amino acid-incorporating system has been obtained from ungerminated wheat germ, which can be stimulated by the addition of uridylic-rich polynucleotides. Polyadenylic and polycytidylic acids fail to stimulate the incorporation of lysine and proline, respectively. The amino acid codons determined by the use of the uridylic-rich polynucleotides coincide almost perfectly with those reported for Escherichia coli. Binding of aminoacyl-sRNA to wheat germ ribosomes can be directed specifically by polynucleotides and does not require the presence of supematant fraction or guanosine triphosphate. Polycytidylic acid failed to promote prolylsRNA binding by ribosomes.