NUCLEOTIDES ADJACENT TO 5'-TERMINUS OF BACTERIOPHAGE RI7 RNA

Information about the 5′-terminal nucleotide triplet of bacteriophage R17 RNA was obtained in order to test the hypothesis that it might be an N-formylmethionine initiator codon. Utilizing the fact that most R17 RNA chains made in vivo contain pppGp--- 5′-termini, a method for determination of the chain length of the 5′-terminal oligonucleotide resulting from pancreatic RNase hydrolysis of R17 RNA was developed. The results suggest that R17 RNA chains made in vivo have the 5′-terminal sequence pppGpXpYp--- (X = purine, Y = pyrimidine). Therefore, an N-formylmethionine initiator codon cannot be present directly at the 5′-terminus of this messenger RNA. © 1968.