Protamines, histones and the genetic code. New evidence for code evaluations.
A new approach is presented to give evidence for the theories of Jukes and Crick (1-3) that at a more primitive stage the genetic code consisted of doublets separated by "comma-bases" rather than true triplets and that G and C or A and U are the exclusive bases used by the primordial code. This approach makes use of the conservation of the histone IV sequence over extremely long periods of time by comparing the amino acid composition of the average vertebrate protein with the one of histone IV, a reconstructed ancestral polypeptide and various nuclear proteins, homologous or otherwise related to it. All protamines studied and the majority of histones show deviations from the average vertebrate protein which are statistically highly significant if the amino acids sufficiently coded for by the first two bases are compared. A similar result is obtained for those amino acids which are sufficiently coded for by the first two bases of the codon and have codons composed of G and C only.
D000595:Amino Acid Sequence; D000818:Animals; D005075:Biological Evolution; D005815:Genetic Code; D006657:Histones; D011479:Protamines; D014714:Vertebrates
D006657:Histones; D011479:Protamines