EST Analyses Accelerate Gene Discovery

EST stands for expressed sequence tag. ESTs are short chains of nucleotide bases (200-800 bases in length) derived from cDNA libraries. That is, they are sequences obtained from complementary DNA (cDNA) which, in turn, is obtained from RNA transcripts. Thus EST sequencing is method of studying gene expression, or the mechanisms for control of transcription, in a cell or organism. At any given time, certain genes in a cell undergo transcription to generate RNA, which is later translated into proteins. Scientists can use RNA preparations and reverse transcriptase enzymes to create a collection of cDNA (the library), then create short sequences (ESTs) for entry into a database. EST analysis is made possible by new technologies such as microarrays and automated sequencing methods, as well as computerized data analysis techniques, and played a significant role in the human genome project.