Abnormal Codon Recognition of Glycyl-tRNA from the Posterior Silk Glands of Bombyx mori

Abstract

Two species of glycine tRNA (tRNA₁^Gly and tRNA₂^Gly) were purified from the posterior silk glands of Bombyx mori. Digestion of tRNA₁^Gly with RNase T1 revealed that this tRNA corresponds to the species which has recently been sequenced by Garel and Keith (1), and Zu_??_iga and Steitz (2), independently. However, the position 9 of our tRNA₁^Gly was occupied by unmodified guanosine instead of m¹G. The codon recognition properties of highly puri-fied tRNA₁^Gly and tRNA₂^Gly were investigated in detail according to the method of Nirenberg and Leder (3). All four glycine codons were recognized by tRNA₁^Gly and by tRNA₂^Gly. These results suggest the presence of abnormal base-pairs between the first base G of the anticodon and all the third bases of the codons, or the recognition by “two-out-of-three” type reading.