A sequence of nucleotides found in comparable regions of DNA or RNA, e.g. in the promoter regions (see operon) of different genes, in which certain bases occur with a frequency significantly greater than that expected by chance. Although such sequences may vary from case to case, it is possible to derive the most likely sequence overall. An example is the Pribnow box of prokaryote promoters. The term is also applied to sequences of amino acids in polypeptides.