title: Codons and nearest-neighbor nucleotide pairs in mammalian messenger RNA.
abstract: The codons in four mammalian messenger RNAs (rabbit beta hemoglobin, rat pre-proinsulin, rat pre-growth hormone and human chorionic somatomammotropin) show a predominance of C and G in third nucleotide positions. The C:U ratio is about 2 to 1, and the G:A ratio is about 4 to 1. The possibility is discussed that this disproportionally resulted from DNA replicative errors that favor C.G pairs over A.T pairs, as found in the E. coli mut T strain. "Nearest neighbor" base pairs ("doublets") in the protein-coding regions of phiX174 and in four mammalian mRNAs have been compared. Mammalian mRNA has a low content of CpG in comparison with expectations from its C and G content.
mesh_terms: D001483:Base Sequence; D006063:Chorionic Gonadotropin / Q000235:genetics; D003062:Codon; D003090:Coliphages / Q000235:genetics*; D005914:Globins / Q000235:genetics; D010928:Placental Lactogen / Q000235:genetics; D011384:Proinsulin / Q000235:genetics; D011498:Protein Precursors / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics*; D012367:RNA, Viral / Q000235:genetics
chemical_list: D006063:Chorionic Gonadotropin; D003062:Codon; D011498:Protein Precursors; D012333:RNA, Messenger; D012367:RNA, Viral; D005914:Globins; D010928:Placental Lactogen; D011384:Proinsulin