expressed sequence tag

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A short partial sequence, typically 200–400 bp long, of a complementary DNA (cDNA) clone. Because cDNAs are prepared by reverse transcription of messenger RNA molecules, ESTs act as markers for genes that are expressed in particular tissues or organs. EST sequence data are held on databases, and researchers use computer programs to search for sequences that correspond to, say, a partial amino-acid sequence for a protein under investigation. The EST sequence can then be used to construct a DNA probe to locate the respective clone from a DNA library.

Subjects: Genetics and Genomics.

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