Readinbg of the lysine codons in the MS 2 coat protein cistron during protein synthesis in vitro

Abstract

The translation of the genetic information contained in the messenger RNA is based on the recognition between codon and anticodon. The first two positians of the codon are read by the anticodon strictly according to the rules of classic base pairing. Wowever, in the reading of the third codon position by the wobble nucleotide of the a~tic~dQ~ a greater degree of freedom must be postulated in order to allow for the discrepancy between the large number of codons in a degenerate code and the limited number of anticodons available for reading them. In his wobble hypothesis [I] Crick has laid down the restrictions which presumably govern the reading of the third codon position. Obviously, the reading of this position must be restricted in alI cases where there would otherwise be a mistake in the synthesized protein. For intance, in the phenyl~~ine~eu~~e codon group QJUU, UUC, UUA and UUG), an anticodon with Gin the wobble position cannot recognize the codons UUA and UUG because that would lead to the in~oduction of phenyl~an~e instead of leucine. We have introduced the term codon family to denote a group of four codons which all code for the same amino acid and we have asked ourselves if the rules of the wobble hypothesis apply as strictly here