Polypeptide sequences coded by complementary DNA strands: A computer investigation of gene polynucleotide sequences

We have analysed both the coding and the complementary strands of many structural genes of known polynucleotide sequence, looking for open reading frames initiated with the AUG codon as a necessary condition for the existence of virtual genes. While in the coding strand we found, as significative virtual gene, only a codon sequence corresponding to the real gene, the analysis of the complementary strand shows, in some cases, virtual gene even longer than the real protein. The case of rabbit β-globin is discussed along with other fea¬tures that make "a priori" indistinguishable, on the basis of actual knowledge of gene structure, the coding from the complementary strands. On the basis of this analysis, we hypothesized the existence of proteins (c.i.p.) coded by the complementary strand of some genes.