Expressed sequence tag

An expressed sequence tag or EST is a short sub-sequence of a transcribed protein-coding or non-protein coding DNA sequence. It was originally intended as a way to identify gene transcripts, but has since been instrumental in gene discovery and sequence determination. An EST is produced by one-shot sequencing of a cloned mRNA, and the resulting sequence is a relatively low quality fragment whose length is limited by current technology to approximately 500 to 800 nucleotides. ESTs are also a useful resource for designing probes for DNA microarrays used to determine gene expression.

External links

• The NCBI Handbook, Part 3, Chapter 21 has a very nice overview.