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Roles of methionine transfer RNA's in protein synthesis in rabbit reticulocytes

1970; Elsevier BV; Volume: 54; Issue: 1 Linguagem: Inglês

10.1016/0022-2836(70)90452-3

1089-8638

N.K. Gupta, Nando K. Chatterjee, Kallol Bose, Saumya Bhaduri, A. C. Chung,

Biochemical and Molecular Research

DEAE-Sephadex column chromatography of crude rabbit liver transfer RNA gives rise to three peaks of methionine-acceptor activity. Only one of these tRNAMet species (tRNAfMet)† could be charged by Escherichia coli synthetase and, as previously reported, could be formylated by E. coli formylase. The other two tRNAMet species (tRNAm1Met and tRNAm2Met) could not be charged by E. coli synthetase. The coding properties of the tRNAMet species were studied in a cell-free protein synthesizing system obtained from rabbit reticulocytes with poly r(A-U-G) messenger and endogenous messenger in reticulocyte ribosomes. These studies indicated that with rabbit reticulocytes, tRNAfMet recognizes specifically the terminal methionine codon (AUG) and transfers methionine to the N-terminal positions of the polypeptide chains while tRNAmMet recognizes specifically the internal methionine codon (AUG) and inserts methionine into the internal positions of the polypeptide chains.