Protocol Online logo
Top : New Forum Archives (2009-): : BioForum Method Discussion Archives

purpose of ESTs - (Jun/08/2003 )


What's the significance of the ESTs in the database?What role does it plays in repeat sequence analysis?And what is the importance of the presence of intron in it?Please let me know how to get details about it?

a countless thanks in advance


ESTs (Expressed Sequence Tag) are "single-pass" cDNA sequences. EST experiment is type of expression analysis, just like RT-PCR, Northern, SAGE, and microarray. They all study gene expression. To generate ESTs, you first create a cDNA library from cell or tissue, then pick hundreds or thousands of clones from the library and sequence the clone (just one pass, no validation, no full length sequence, usually from polyA tail, but can also sequence from 5' and the middle. )

take a look on NCBI dbEST

EST has no much to do with repeat sequence and intron, because it is expressed sequence.


Thank you sir,

Actually i want the EST's role in ALU repeats which are sometimes present in alternatively spliced exons. sometimes we can see a scenario in which it is present in intron also. Please help me out.

Thanks in advance


To Pretti_louis

I think you would like to find out a marker form ALU repeat, isn't it? and to discriminate those of exon and intron by using EST as a marker?
RASSEN have gave you information about EST and you might be try further information about sequence marker.


The EST are short sequences found by several persons while they were doing their work. They put these sequences available on a database.
You might want to read Wittenberger's paper where he uses ESTs to discover new GPCRs (2001).
Since ESTs are expressed sequences from various tissues, from various organs, from various animals/plants, it has nothing to do with a specific form of sequence such as a repeat motif. Only, you can screen the EST database to find where your motif is expressed.
Hope I could help. ;)


newbie here and would like to share my brief experience with repeats in ESTs.
Though ESTs are all coding genes, the presence of SSR-EST (simple sequence repeats) are quite significant especially in eukaryotic organism. Their presence range from 3.4% from 91035 est sequencesfrom a species of vertabrate based on a brief analysis that i have done.
I was quite baffled at first but their presence somehow points to the possibility of these repeats do play a function in gene expression.
any comments apprciated :)

my 2 cents