Sequence tagged site (STS)
Short (200 to 500 base pairs) DNA sequence that has a single occurrence in the human genome and whose location and base sequence are known. Detectable by polymerase chain reaction, STSs are useful for localizing and orienting the mapping and sequence data reported from many different laboratories and serve as landmarks on the developing physical map of the human genome. Expressed sequence tags (ESTs) are STSs derived from cDNAs.
hope it helps
Sequence Tagged Sites (STS) markers have recently been developped in crop plants and more in trees. A STS is a unique, simple-copy segment of the genome whose DNA sequence is known and which can be amplified by specific PCR. When STS loci contain DNA length polymorphisms (e.g. simple sequence length polymorphisms, SSLPs), they become valuable genetic markers.
The main advantage of STS loci lies in the speed with which they can be analyzed once PCR primer pairs have been identified. Like RFLP loci, STS loci can be analyzed as co-dominance genetic markers and can in theory, be studied in member of the species or closely related species, provided that the DNA sequence is conserved at the PCR primer sites. Analysis with STS markers thus combines the speed of the RAPD markers with the informativeness of RFLP markers.