Methionine transfer ribonucleic acids of avian myeloblastosis virus.

Chick-embryo cells contain four isoaccepting species of methionine transfer RNA (I-IV). One species (I) is the initiator, tRNA(f) (Met), and the others (II, III, and IV) are the donors of internal methionyl residues (tRNA(m) (Met)). Over 85% of the tRNA(Met) in purified avian myeloblastosis virus consists of one tRNA(m) (Met) species, which resembles host-cell tRNA(Met) IV with respect to chromatographic properties on RPC-5, electrophoretic mobility of the terminal methionyl-oligonucleotide, and activity in cell-free protein synthesis in response to synthetic and natural messenger RNAs. Thus, tRNA(Met) IV of avian myeloblastosis virus is structurally indistinguishable from the corresponding host-cell species, and, although not involved in initiation of viral protein synthesis, is able to function in peptide-chain elongation.