Expressed sequence tags , data source

Potato type II (Potll) inhibitors are disulfide-rich peptides of approximately 50 amino acids in size. They were first discovered in leaves, seeds, and other organs of Solanaceae and are a source of much interest as plant defense proteins. Recently, Barta et analyzed expressed sequence tag (EST) and genomic data and discovered 11 genes that code for Potll inhibitors in various monocotyledonous and dicotyledonous plants. Potll inhibitors are expressed as large precursor proteins that contain up to eight sequence repeats of the inhibitor precursor. In one particularly fascinating case from the ornamental tobacco (N. data), the precursor adopts a circular permuted structure.Barta et al. observed that genes outside the Solanaceae family seem... 

Without any doubt, mass spectrometry is now the most efficient way to identify proteins [75-78], The method is based on comparison of the data obtained from the mass spectrometry with those predicted for all the proteins contained in a database. The efficiency of the method results from the development of mass spectrometry into a rapid and sensitive method to analyse peptides and proteins and also from the availability of larger and larger databases. In October 2006, these databases contained more than 2400000 non-redundant sequences. Furthermore, the data obtained from genomic sequences after translation in the six lecture frames also can be used. The databases based on expressed sequence tags (ESTs) are another usable source for search. They are composed of sequences based on cDNA fast sequencing. They are limited to short lengths, about 300 bases, and contain many errors but they correspond to coding sequences. Despite their defects, they are very useful for identification of proteins by mass spectrometry [79]. 

Gene expression databases can be made from two sources, ESTs (Expressed Sequence Tags) or DNA chip expression data. 

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