Abnormal codon recognition of glycyl-tRNA from the posterior silk glands of Bombyx mori.

Two species of glycine tRNA (tRNA1Gly and tRNA2Gly) were purified from the posterior silk glands of Bombyx mori. Digestion of tRNA1Gly wit RNase T1 revealed that this tRNA corresponds to the species which has recently been sequenced by Garel and Keith (1), and Züniga and Steitz (2), independently. However, the position 9 of our tRNA2Gly was occupied by unmodified guanosine instead of m1G. The codon recognition properties of highly purified tRNA1Gly and tRNA2Gly were investigated in detail according to the method of Nirenberg and Leder (3). All four glycine codons were recognized by tRNA1Gly and by tRNA2Gly. 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.