(Science: molecular biology) short tagged tracts of dNA sequence (200 to 500 base pairs) that is operationally unique and has a single occurrence in the human genome. Their location and base sequence are known and therefore they can be used as landmarks in genome mapping.
They can be detected by the polymerase chain reaction in the presence of all other genomic sequences). Sequence-tagged sites are useful for mapping the sequence data reported from different laboratories and provide a framework for the physical map of the human genome. The overwhelming advantage of sequence-tagged sites over mapping landmarks defined through other methods is that the method can be completely described as information in a database.
expressed sequence tags are sequence tagged sites derived from cDNAs.